GN13BjarneStroustrupKeynote_high.ass

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Dialogue: 0,0:00:00.00,0:00:09.04,Default,,0000,0000,0000,,{\fs36\b1\pos(502,68)} {\c&HD201D6&} 本字幕由 avplayer.org 社区出品
Dialogue: 0,0:00:00.20,0:00:04.58,Default,,0000,0000,0000,,{\pos(517,299)}gentleman please welcome Charles Torre
Dialogue: 0,0:00:09.12,0:00:11.28,Default,,0000,0000,0000,,excellent. thanks for showing up
Dialogue: 0,0:00:11.38,0:00:13.76,Default,,0000,0000,0000,,it's great to able to do goingnative again.
Dialogue: 0,0:00:13.82,0:00:18.76,Default,,0000,0000,0000,,last year was awesome, wonderful to see all you people, all you programmers in the audience
Dialogue: 0,0:00:19.28,0:00:20.68,Default,,0000,0000,0000,,there is people on-line
Dialogue: 0,0:00:20.68,0:00:23.34,Default,,0000,0000,0000,,thanks to the channel9 team for streaming this live,
Dialogue: 0,0:00:23.42,0:00:25.88,Default,,0000,0000,0000,,very appreciate that. so you can ask questions on-line.
Dialogue: 0,0:00:25.97,0:00:29.56,Default,,0000,0000,0000,,But we gona take questions from people on this rooms priority you came.
Dialogue: 0,0:00:29.72,0:00:30.65,Default,,0000,0000,0000,,That's excellent.
Dialogue: 0,0:00:31.22,0:00:34.51,Default,,0000,0000,0000,,We have a great 3 days for you.
Dialogue: 0,0:00:34.52,0:00:37.71,Default,,0000,0000,0000,,today we gona say pretty much iso for day1 and day2.
Dialogue: 0,0:00:37.73,0:00:42.53,Default,,0000,0000,0000,,mainly focus on standard c++.
Dialogue: 0,0:00:42.92,0:00:46.90,Default,,0000,0000,0000,,day3 we gonna kind of  some windows
Dialogue: 0,0:00:47.05,0:00:50.74,Default,,0000,0000,0000,,some more vc++ with iso could be excellent
Dialogue: 0,0:00:52.84,0:00:57.36,Default,,0000,0000,0000,,I'd like to introduce our key note speaker.
Dialogue: 0,0:00:57.39,0:00:59.79,Default,,0000,0000,0000,,so wonderful to have Bjarne Stroupstrup to appear.
Dialogue: 0,0:01:00.11,0:01:02.02,Default,,0000,0000,0000,,the creator of c++
Dialogue: 0,0:01:02.27,0:01:04.88,Default,,0000,0000,0000,,he's gonna teach us a little bit about the essences.
Dialogue: 0,0:01:05.05,0:01:06.83,Default,,0000,0000,0000,,thanks for come-ing !
Dialogue: 0,0:01:07.10,0:01:10.12,Default,,0000,0000,0000,,------
Dialogue: 0,0:01:11.20,0:01:15.13,Default,,0000,0000,0000,,OK, here. welcome, seams the mic working.
Dialogue: 0,0:01:17.02,0:01:25.56,Default,,0000,0000,0000,,so, in the next couple of days, you are going to hear a lot about the latest and greatest in c++.
Dialogue: 0,0:01:25.60,0:01:30.49,Default,,0000,0000,0000,,you are going to hear a lot about advanced tech and new features.
Dialogue: 0,0:01:30.80,0:01:36.14,Default,,0000,0000,0000,,and I decide that in the keynote, I couldn't go too much into that.
Dialogue: 0,0:01:36.21,0:01:38.62,Default,,0000,0000,0000,,so I'm going to try to do the opposite.
Dialogue: 0,0:01:38.84,0:01:43.07,Default,,0000,0000,0000,,I'm going to try and focus on what is the essence of c++ .
Dialogue: 0,0:01:43.36,0:01:48.96,Default,,0000,0000,0000,,what is it that's been constant over the decades.
Dialogue: 0,0:01:49.05,0:01:55.38,Default,,0000,0000,0000,,and basically what is it that's  kept c++ alive and kicking.
Dialogue: 0,0:01:55.45,0:02:02.54,Default,,0000,0000,0000,,of course I cann't quite insist showing some new and nice stuff
Dialogue: 0,0:02:02.57,0:02:08.66,Default,,0000,0000,0000,,so the last 15min or so will be about something from c++14.
Dialogue: 0,0:02:09.25,0:02:14.86,Default,,0000,0000,0000,,but basically I'll talk about aims and constraints , and the development first.
Dialogue: 0,0:02:15.16,0:02:19.50,Default,,0000,0000,0000,,I'm trying to explain c++ in four slides.
Dialogue: 0,0:02:19.69,0:02:27.90,Default,,0000,0000,0000,,and then going to some details of resource management, oop , ge, what challenge ahead.
Dialogue: 0,0:02:28.05,0:02:37.85,Default,,0000,0000,0000,,so, basically, that is what we want , out of a programming language that is aim among things for system programming.
Dialogue: 0,0:02:38.14,0:02:39.77,Default,,0000,0000,0000,,We want type safety.
Dialogue: 0,0:02:39.94,0:02:44.05,Default,,0000,0000,0000,,That will be ideal, we can't be perfect about that
Dialogue: 0,0:02:44.17,0:02:48.14,Default,,0000,0000,0000,,with the need to deal close to the hardware. and with the C inheritance .
Dialogue: 0,0:02:48.25,0:02:51.54,Default,,0000,0000,0000,,but it's an idea , it's something we aim to improve.
Dialogue: 0,0:02:51.88,0:02:53.85,Default,,0000,0000,0000,,We want resource safety.
Dialogue: 0,0:02:54.22,0:02:56.94,Default,,0000,0000,0000,,that is not just memory.
Dialogue: 0,0:02:57.08,0:03:01.51,Default,,0000,0000,0000,,so i'm going to argue that we we really don't want to leak anything.
Dialogue: 0,0:03:01.60,0:03:07.71,Default,,0000,0000,0000,,and "things" can be, things like locks and file handles, not just memory.
Dialogue: 0,0:03:07.74,0:03:09.48,Default,,0000,0000,0000,,I'm going to talk about performance
Dialogue: 0,0:03:09.51,0:03:10.73,Default,,0000,0000,0000,,because , well,
Dialogue: 0,0:03:10.89,0:03:12.62,Default,,0000,0000,0000,,that is important.
Dialogue: 0,0:03:12.78,0:03:17.04,Default,,0000,0000,0000,,if it isn't important to you , that might be better language for you to do.
Dialogue: 0,0:03:17.22,0:03:24.33,Default,,0000,0000,0000,,predictability is very important for very large component of the c++ world.
Dialogue: 0,0:03:24.38,0:03:30.54,Default,,0000,0000,0000,,er, dealing with hardware, dealing with things that has to be happen quickly or reliably or repeatedly .
Dialogue: 0,0:03:30.74,0:03:33.06,Default,,0000,0000,0000,,and we want languages that can be taught.
Dialogue: 0,0:03:33.38,0:03:39.56,Default,,0000,0000,0000,,we want something that is no more complex than the needs to be for the tasks is doing.
Dialogue: 0,0:03:39.78,0:03:43.02,Default,,0000,0000,0000,,and of course we want to be able to read what we are doing.
Dialogue: 0,0:03:43.11,0:03:46.16,Default,,0000,0000,0000,,you can writ unreadable code in any language of course.
Dialogue: 0,0:03:46.40,0:03:51.80,Default,,0000,0000,0000,,but, we want to be able to write some thing on a good day
Dialogue: 0,0:03:51.93,0:03:56.23,Default,,0000,0000,0000,,that people say, "wow, this is realy nice and clean an clear."
Dialogue: 0,0:03:56.47,0:04:02.96,Default,,0000,0000,0000,,these are the aims we much better added today than we were 20 years ago
Dialogue: 0,0:04:03.16,0:04:08.48,Default,,0000,0000,0000,,and will be actually much better next year when we get c++14
Dialogue: 0,0:04:09.12,0:04:11.76,Default,,0000,0000,0000,,and , we want...
Dialogue: 0,0:04:11.83,0:04:20.36,Default,,0000,0000,0000,,the primary concerns of mine, is system programming, embedded systems, resource constrain systems, and large systems.
Dialogue: 0,0:04:20.54,0:04:22.26,Default,,0000,0000,0000,,that is ... err...
Dialogue: 0,0:04:22.36,0:04:28.08,Default,,0000,0000,0000,,so, strictly, the domain of high qualified professional programmers.
Dialogue: 0,0:04:28.41,0:04:34.35,Default,,0000,0000,0000,,and it may very well means that if you have a tool for that, it's good for a lot of other things.
Dialogue: 0,0:04:34.38,0:04:37.51,Default,,0000,0000,0000,,that was one of my surprises early on was
Dialogue: 0,0:04:37.61,0:04:41.37,Default,,0000,0000,0000,,.. so many systems has a clue to it
Dialogue: 0,0:04:41.37,0:04:44.70,Default,,0000,0000,0000,,where what I mostly interest in is essential
Dialogue: 0,0:04:44.80,0:04:50.61,Default,,0000,0000,0000,,and then c++ is so general, that it well do the rest also.
Dialogue: 0,0:04:50.80,0:04:59.89,Default,,0000,0000,0000,,so, c++ is expert friendly, definitely. and, the problem is , that's not enough.
Dialogue: 0,0:05:00.07,0:05:05.13,Default,,0000,0000,0000,,if it is only expert friendly,  if it just expert friendly, that's nothing for novices.
Dialogue: 0,0:05:05.60,0:05:11.16,Default,,0000,0000,0000,,we must involve the language into something that is a bit more friendly to novices
Dialogue: 0,0:05:11.23,0:05:21.46,Default,,0000,0000,0000,,without giving in an inch of / bytes and cycle for the experts, what they really needs is bytes an cycles.
Dialogue: 0,0:05:21.67,0:05:26.91,Default,,0000,0000,0000,,so part of this is my answer to what is c++.
Dialogue: 0,0:05:27.06,0:05:33.71,Default,,0000,0000,0000,,I .. I  .., I have my ideas that's not necessary the same as anybody else is.
Dialogue: 0,0:05:33.92,0:05:38.59,Default,,0000,0000,0000,,there are probably a big border than what you hear in most places
Dialogue: 0,0:05:38.83,0:05:41.43,Default,,0000,0000,0000,,that is I try to see the whole elephant
Dialogue: 0,0:05:41.44,0:05:43.36,Default,,0000,0000,0000,,and I find that
Dialogue: 0,0:05:43.39,0:05:46.60,Default,,0000,0000,0000,,in forums on the web and conferences as such
Dialogue: 0,0:05:46.60,0:05:49.02,Default,,0000,0000,0000,,people play Blind Men and the Elephant
Dialogue: 0,0:05:49.02,0:05:53.10,Default,,0000,0000,0000,,and they are absolutely certain that their part of the elephant is the whole beast.
Dialogue: 0,0:05:53.34,0:05:54.36,Default,,0000,0000,0000,,they are wrong.
Dialogue: 0,0:05:54.86,0:05:58.30,Default,,0000,0000,0000,,so this is my summery of c++
Dialogue: 0,0:05:58.30,0:05:59.97,Default,,0000,0000,0000,,if you have to do in one slide.
Dialogue: 0,0:06:00.17,0:06:04.71,Default,,0000,0000,0000,,it's a language that provides light weight abstraction facilities
Dialogue: 0,0:06:04.96,0:06:09.72,Default,,0000,0000,0000,,and its key strength scenario is where you build software infrastructure
Dialogue: 0,0:06:09.72,0:06:14.42,Default,,0000,0000,0000,,and where you have resource constraint applications.
Dialogue: 0,0:06:14.59,0:06:15.81,Default,,0000,0000,0000,,it's not the elephant
Dialogue: 0,0:06:15.95,0:06:17.18,Default,,0000,0000,0000,,it's light weight
Dialogue: 0,0:06:17.33,0:06:19.72,Default,,0000,0000,0000,,it's the abstraction you can build
Dialogue: 0,0:06:19.84,0:06:23.60,Default,,0000,0000,0000,,that is anybody can build a really slow
Dialogue: 0,0:06:24.02,0:06:25.80,Default,,0000,0000,0000,,big abstraction.
Dialogue: 0,0:06:26.39,0:06:33.74,Default,,0000,0000,0000,,but, building a point or coordinate or complex number
Dialogue: 0,0:06:33.84,0:06:39.33,Default,,0000,0000,0000,,that you can afford in competition language that is building facilities like that, is hard.
Dialogue: 0,0:06:39.36,0:06:41.53,Default,,0000,0000,0000,,and that's what c++'s strength is.
Dialogue: 0,0:06:41.99,0:06:45.28,Default,,0000,0000,0000,,c++ is developed
Dialogue: 0,0:06:45.28,0:06:53.87,Default,,0000,0000,0000,,comes from two of the main lines of development of programming language.
Dialogue: 0,0:06:54.01,0:06:56.40,Default,,0000,0000,0000,,the lower line here
Dialogue: 0,0:06:56.40,0:06:58.62,Default,,0000,0000,0000,,were basically exploit the hardware
Dialogue: 0,0:06:58.62,0:07:00.26,Default,,0000,0000,0000,,start with assembler
Dialogue: 0,0:07:00.44,0:07:01.80,Default,,0000,0000,0000,,went though BCPL
Dialogue: 0,0:07:01.80,0:07:02.39,Default,,0000,0000,0000,,and C
Dialogue: 0,0:07:02.39,0:07:08.06,Default,,0000,0000,0000,,and C++ gets a lot of its low level stuff from C.
Dialogue: 0,0:07:09.47,0:07:10.64,Default,,0000,0000,0000,,you can see people there
Dialogue: 0,0:07:10.68,0:07:12.11,Default,,0000,0000,0000,,, that's of course Dennis Ritchie
Dialogue: 0,0:07:12.11,0:07:14.23,Default,,0000,0000,0000,,that's David Wheeler
Dialogue: 0,0:07:14.23,0:07:15.64,Default,,0000,0000,0000,,my thesis advisor
Dialogue: 0,0:07:15.64,0:07:19.09,Default,,0000,0000,0000,,and one of the ten people claim to written the first compiler
Dialogue: 0,0:07:19.52,0:07:24.90,Default,,0000,0000,0000,,he can also claim to have written the first program even running on a store program computer.
Dialogue: 0,0:07:25.21,0:07:28.09,Default,,0000,0000,0000,,so this is .. a .. good thing
Dialogue: 0,0:07:28.09,0:07:28.34,Default,,0000,0000,0000,,good
Dialogue: 0,0:07:28.57,0:07:28.99,Default,,0000,0000,0000,,good
Dialogue: 0,0:07:29.17,0:07:31.98,Default,,0000,0000,0000,,long tradition exploit the hardware maximally.
Dialogue: 0,0:07:32.32,0:07:33.16,Default,,0000,0000,0000,,on the other hand
Dialogue: 0,0:07:33.16,0:07:34.38,Default,,0000,0000,0000,,the biggest improvement
Dialogue: 0,0:07:34.38,0:07:36.28,Default,,0000,0000,0000,,in programming languages ever
Dialogue: 0,0:07:36.28,0:07:38.46,Default,,0000,0000,0000,,was done by Backus' team at IBM.
Dialogue: 0,0:07:38.82,0:07:42.67,Default,,0000,0000,0000,,when they decide to improve productivity of programmers
Dialogue: 0,0:07:42.67,0:07:46.59,Default,,0000,0000,0000,,by letting programmers write in a language that fit for humans
Dialogue: 0,0:07:46.59,0:07:49.45,Default,,0000,0000,0000,,instead of those load&store hardware close stuff.
Dialogue: 0,0:07:49.63,0:07:50.87,Default,,0000,0000,0000,,so they got Fortran
Dialogue: 0,0:07:50.87,0:07:51.76,Default,,0000,0000,0000,,and you could get
Dialogue: 0,0:07:52.09,0:07:52.99,Default,,0000,0000,0000,,... err ...
Dialogue: 0,0:07:53.10,0:07:55.71,Default,,0000,0000,0000,,programs written in exactly your own language
Dialogue: 0,0:07:56.03,0:07:58.91,Default,,0000,0000,0000,,provide you are certain kind of engineer
Dialogue: 0,0:07:58.91,0:07:58.98,Default,,0000,0000,0000,,or
Dialogue: 0,0:07:58.99,0:08:01.40,Default,,0000,0000,0000,,certain kind of scientist.
Dialogue: 0,0:08:01.70,0:08:03.82,Default,,0000,0000,0000,,so that's how we go Fortran.
Dialogue: 0,0:08:03.96,0:08:06.86,Default,,0000,0000,0000,,and as soon as this idea was heard
Dialogue: 0,0:08:07.00,0:08:08.68,Default,,0000,0000,0000,,everybody wanted their language
Dialogue: 0,0:08:08.68,0:08:11.78,Default,,0000,0000,0000,,from their particular domain.
Dialogue: 0,0:08:11.80,0:08:13.80,Default,,0000,0000,0000,,so the business people got Cobol
Dialogue: 0,0:08:14.01,0:08:17.24,Default,,0000,0000,0000,,where you can say business like things
Dialogue: 0,0:08:17.87,0:08:21.95,Default,,0000,0000,0000,,copy files, write to tape and things like that.
Dialogue: 0,0:08:22.30,0:08:22.78,Default,,0000,0000,0000,,err ....
Dialogue: 0,0:08:22.81,0:08:23.03,Default,,0000,0000,0000,,and
Dialogue: 0,0:08:23.07,0:08:23.38,Default,,0000,0000,0000,,and
Dialogue: 0,0:08:23.43,0:08:26.04,Default,,0000,0000,0000,,very soon , there was a couple of hundreds of languages.
Dialogue: 0,0:08:26.33,0:08:27.97,Default,,0000,0000,0000,,and it is a terrible mess.
Dialogue: 0,0:08:28.10,0:08:30.81,Default,,0000,0000,0000,,because, every language that was good at one thing
Dialogue: 0,0:08:31.14,0:08:36.81,Default,,0000,0000,0000,,you speak one language of one subset of the computing community.
Dialogue: 0,0:08:37.28,0:08:39.69,Default,,0000,0000,0000,,and, so the brilliant ideal here
Dialogue: 0,0:08:40.04,0:08:42.02,Default,,0000,0000,0000,,from Kristen Nygaard
Dialogue: 0,0:08:42.33,0:08:45.35,Default,,0000,0000,0000,,was to generalize these thing
Dialogue: 0,0:08:45.35,0:08:45.85,Default,,0000,0000,0000,,ok
Dialogue: 0,0:08:46.15,0:08:47.54,Default,,0000,0000,0000,,if you have a concept
Dialogue: 0,0:08:47.84,0:08:49.08,Default,,0000,0000,0000,,if you have an idea
Dialogue: 0,0:08:49.50,0:08:50.61,Default,,0000,0000,0000,,in your head
Dialogue: 0,0:08:50.72,0:08:52.07,Default,,0000,0000,0000,,on you blackboard
Dialogue: 0,0:08:52.30,0:08:53.06,Default,,0000,0000,0000,,or what ever
Dialogue: 0,0:08:53.06,0:08:56.09,Default,,0000,0000,0000,,you should be able to put it into a language in general.
Dialogue: 0,0:08:56.27,0:09:00.37,Default,,0000,0000,0000,,so instead of building language around special purpose concept
Dialogue: 0,0:09:00.37,0:09:03.68,Default,,0000,0000,0000,,you provide the facility for building new things.
Dialogue: 0,0:09:03.84,0:09:06.48,Default,,0000,0000,0000,,they called it classes, and class hierarchies
Dialogue: 0,0:09:07.98,0:09:13.03,Default,,0000,0000,0000,,here comes the line of general purpose abstraction from the hardware
Dialogue: 0,0:09:13.40,0:09:14.73,Default,,0000,0000,0000,,and I borrow that
Dialogue: 0,0:09:14.87,0:09:16.73,Default,,0000,0000,0000,,and got the initial c++.
Dialogue: 0,0:09:16.81,0:09:19.62,Default,,0000,0000,0000,,we've been developing that ever since
Dialogue: 0,0:09:20.00,0:09:23.56,Default,,0000,0000,0000,,and that's been a lot of development in the world of course
Dialogue: 0,0:09:23.79,0:09:25.63,Default,,0000,0000,0000,,but I'm talking about this line here.
Dialogue: 0,0:09:25.98,0:09:26.30,Default,,0000,0000,0000,,so
Dialogue: 0,0:09:26.46,0:09:30.48,Default,,0000,0000,0000,,what we need, is to be able to do things really well close to the hardware
Dialogue: 0,0:09:30.56,0:09:31.63,Default,,0000,0000,0000,,as well as anybody
Dialogue: 0,0:09:31.97,0:09:32.60,Default,,0000,0000,0000,,and
Dialogue: 0,0:09:32.75,0:09:43.42,Default,,0000,0000,0000,,provide general purpose abstraction so that we can actually get the concepts we need in our program as opposed to always talk about bits and bytes.
Dialogue: 0,0:09:44.03,0:09:46.36,Default,,0000,0000,0000,,so, c++ is of course not perfect
Dialogue: 0,0:09:46.52,0:09:50.15,Default,,0000,0000,0000,,anybody who will claims to have a prefect language
Dialogue: 0,0:09:51.10,0:09:52.36,Default,,0000,0000,0000,,is either sale man
Dialogue: 0,0:09:52.45,0:09:53.32,Default,,0000,0000,0000,,or fool
Dialogue: 0,0:09:53.40,0:09:54.08,Default,,0000,0000,0000,,or both
Dialogue: 0,0:09:57.29,0:10:03.75,Default,,0000,0000,0000,,c++ doesn't actually aim to do everything for everybody.
Dialogue: 0,0:10:03.87,0:10:08.28,Default,,0000,0000,0000,,there are things that are less interesting and things that
Dialogue: 0,0:10:08.68,0:10:10.07,Default,,0000,0000,0000,,you just don't need
Dialogue: 0,0:10:10.14,0:10:11.31,Default,,0000,0000,0000,,say that, the efficiency
Dialogue: 0,0:10:11.50,0:10:12.40,Default,,0000,0000,0000,,close to hardware things
Dialogue: 0,0:10:13.21,0:10:14.96,Default,,0000,0000,0000,,or you don't need the abstraction.
Dialogue: 0,0:10:15.33,0:10:16.60,Default,,0000,0000,0000,,there are alternatives
Dialogue: 0,0:10:16.84,0:10:18.87,Default,,0000,0000,0000,,we are not trying to be every thing for everybody.
Dialogue: 0,0:10:19.29,0:10:21.76,Default,,0000,0000,0000,,you has a solid fundamental model
Dialogue: 0,0:10:22.13,0:10:26.39,Default,,0000,0000,0000,,despite what you might have heard, or what your professors might have told you in class.
Dialogue: 0,0:10:26.60,0:10:31.47,Default,,0000,0000,0000,,that quite solid model for what.  C++ is not try to conventional about that.
Dialogue: 0,0:10:32.00,0:10:32.37,Default,,0000,0000,0000,,but
Dialogue: 0,0:10:32.77,0:10:36.87,Default,,0000,0000,0000,,basically has C's model of the hardware
Dialogue: 0,0:10:36.87,0:10:43.78,Default,,0000,0000,0000,,and has facilities for principle to add new concept to a program.
Dialogue: 0,0:10:44.16,0:10:48.39,Default,,0000,0000,0000,,and then this has been refined for 30+ years
Dialogue: 0,0:10:48.68,0:10:49.72,Default,,0000,0000,0000,,that is,  it works
Dialogue: 0,0:10:51.70,0:10:54.51,Default,,0000,0000,0000,,this also means, that it has a lot of "what's"
Dialogue: 0,0:10:54.86,0:10:56.86,Default,,0000,0000,0000,,it also means we know the "what's".
Dialogue: 0,0:10:57.34,0:10:59.67,Default,,0000,0000,0000,,people very often choose something new
Dialogue: 0,0:10:59.85,0:11:02.59,Default,,0000,0000,0000,,because, well, they haven't learn it's weakness yet
Dialogue: 0,0:11:02.75,0:11:03.75,Default,,0000,0000,0000,,so it looks perfect.
Dialogue: 0,0:11:04.30,0:11:07.00,Default,,0000,0000,0000,,we know the problems of c++
Dialogue: 0,0:11:07.25,0:11:09.18,Default,,0000,0000,0000,,that's partly an advantage
Dialogue: 0,0:11:09.39,0:11:11.93,Default,,0000,0000,0000,,long term stability is a feature.
Dialogue: 0,0:11:12.55,0:11:17.30,Default,,0000,0000,0000,,that is in the despoil compatibility stuff and crud
Dialogue: 0,0:11:17.73,0:11:19.52,Default,,0000,0000,0000,,you find that
Dialogue: 0,0:11:20.18,0:11:25.76,Default,,0000,0000,0000,,it is really nice that, my programs from ten years ago still runs.
Dialogue: 0,0:11:26.09,0:11:31.86,Default,,0000,0000,0000,,it is really nice because it's sort of assures that our program will run in ten years again.
Dialogue: 0,0:11:32.09,0:11:36.10,Default,,0000,0000,0000,,we trying not to break old code
Dialogue: 0,0:11:36.30,0:11:40.80,Default,,0000,0000,0000,,and performance we want to be a match for everything in usually we are.
Dialogue: 0,0:11:41.01,0:11:49.64,Default,,0000,0000,0000,,and this leads to a set of interesting applications for instance that are very widely used.
Dialogue: 0,0:11:49.89,0:11:51.46,Default,,0000,0000,0000,,it actually
Dialogue: 0,0:11:51.68,0:11:56.44,Default,,0000,0000,0000,,what c++ offers clearly pays off for somebody
Dialogue: 0,0:11:56.66,0:11:59.24,Default,,0000,0000,0000,,otherwise they wouldn't be using it.
Dialogue: 0,0:11:59.55,0:12:03.32,Default,,0000,0000,0000,,so i'm going to go into this a little bit detail.
Dialogue: 0,0:12:04.25,0:12:09.62,Default,,0000,0000,0000,,i'm going to try and get c++ down to just four slides.
Dialogue: 0,0:12:10.08,0:12:11.49,Default,,0000,0000,0000,,and the rest is details.
Dialogue: 0,0:12:11.77,0:12:13.40,Default,,0000,0000,0000,,if you understand int and vector
Dialogue: 0,0:12:13.98,0:12:15.61,Default,,0000,0000,0000,,you understand c++
Dialogue: 0,0:12:15.61,0:12:17.41,Default,,0000,0000,0000,,and there are a lot of details.
Dialogue: 0,0:12:17.54,0:12:19.10,Default,,0000,0000,0000,,but don't get lost in them
Dialogue: 0,0:12:20.10,0:12:20.82,Default,,0000,0000,0000,,that's the point.
Dialogue: 0,0:12:21.00,0:12:22.18,Default,,0000,0000,0000,,btw
Dialogue: 0,0:12:22.71,0:12:24.86,Default,,0000,0000,0000,,I've just written another book
Dialogue: 0,0:12:24.86,0:12:25.80,Default,,0000,0000,0000,,it's very thin
Dialogue: 0,0:12:26.07,0:12:30.09,Default,,0000,0000,0000,,180 pages of stuff plus an index
Dialogue: 0,0:12:30.35,0:12:34.43,Default,,0000,0000,0000,,which claims to present all of c++
Dialogue: 0,0:12:34.73,0:12:37.40,Default,,0000,0000,0000,,at certain level of detail.
Dialogue: 0,0:12:37.61,0:12:40.36,Default,,0000,0000,0000,,so, if you actually are an inexperienced programmer
Dialogue: 0,0:12:40.58,0:12:43.20,Default,,0000,0000,0000,,here is where you can get an idea of c++.
Dialogue: 0,0:12:43.33,0:12:46.39,Default,,0000,0000,0000,,so, that's the end of the advertising.  for now.
Dialogue: 0,0:12:46.96,0:12:47.59,Default,,0000,0000,0000,,er
Dialogue: 0,0:12:47.75,0:12:48.19,Default,,0000,0000,0000,,so
Dialogue: 0,0:12:48.39,0:12:49.18,Default,,0000,0000,0000,,what do we do
Dialogue: 0,0:12:49.18,0:12:50.70,Default,,0000,0000,0000,,the c++ first of all,
Dialogue: 0,0:12:50.94,0:12:53.08,Default,,0000,0000,0000,,we have to map things to hardware
Dialogue: 0,0:12:53.34,0:12:55.96,Default,,0000,0000,0000,,the hardware is where programs run.
Dialogue: 0,0:12:56.53,0:13:00.64,Default,,0000,0000,0000,,they don't run in mathematical abstractions. they run on hardware.
Dialogue: 0,0:13:00.96,0:13:05.54,Default,,0000,0000,0000,,and basically the primitives operation are instructions of the machine.
Dialogue: 0,0:13:09.66,0:13:18.47,Default,,0000,0000,0000,,we have value types (many of them) map directly to machine instructions, some don't. but they are simple. they are values.
Dialogue: 0,0:13:18.84,0:13:23.88,Default,,0000,0000,0000,,if you understand integer , you understand about anything that is a values
Dialogue: 0,0:13:23.88,0:13:28.04,Default,,0000,0000,0000,,you can copy an integer, you can do things to it.
Dialogue: 0,0:13:28.30,0:13:30.11,Default,,0000,0000,0000,,the other kinds are handles
Dialogue: 0,0:13:30.28,0:13:35.37,Default,,0000,0000,0000,,they have handle to control access to values.
Dialogue: 0,0:13:35.68,0:13:36.61,Default,,0000,0000,0000,,so, here for instance
Dialogue: 0,0:13:36.61,0:13:40.35,Default,,0000,0000,0000,,we have a vector that keeps track of how many elements there are
Dialogue: 0,0:13:41.07,0:13:47.00,Default,,0000,0000,0000,,and give you a subscript operation and copy operation and things like that to manipulate the value.
Dialogue: 0,0:13:47.20,0:13:49.07,Default,,0000,0000,0000,,and there is a lot of things like that
Dialogue: 0,0:13:49.39,0:13:52.32,Default,,0000,0000,0000,,but those are two fundamental building blocks we've got
Dialogue: 0,0:13:52.62,0:13:55.60,Default,,0000,0000,0000,,and we compose them by simple concatenation.
Dialogue: 0,0:13:55.87,0:13:59.86,Default,,0000,0000,0000,,that's what happens to an array, you put objects next to each other.
Dialogue: 0,0:14:00.04,0:14:06.31,Default,,0000,0000,0000,,and classes/structs where you put them next to each other usually considered different dimension.
Dialogue: 0,0:14:06.53,0:14:08.76,Default,,0000,0000,0000,,but basically there is nothing more to it.
Dialogue: 0,0:14:08.88,0:14:12.22,Default,,0000,0000,0000,,there're ways of composing these basic things
Dialogue: 0,0:14:12.46,0:14:18.61,Default,,0000,0000,0000,,and when you look at your code. you can sort of think about what is in the memory and understand it
Dialogue: 0,0:14:18.81,0:14:23.80,Default,,0000,0000,0000,,and when it comes to an primitive operation you can see which primitive operations are done.
Dialogue: 0,0:14:25.16,0:14:30.54,Default,,0000,0000,0000,,then, to get away from this very concrete low level view
Dialogue: 0,0:14:31.38,0:14:32.69,Default,,0000,0000,0000,,we have classes
Dialogue: 0,0:14:33.08,0:14:37.48,Default,,0000,0000,0000,,the most important part of  classes I think acturally is constructors and destructors.
Dialogue: 0,0:14:38.76,0:14:40.52,Default,,0000,0000,0000,,we define ourself a new type
Dialogue: 0,0:14:41.22,0:14:44.45,Default,,0000,0000,0000,,and when we initialize it
Dialogue: 0,0:14:44.86,0:14:45.89,Default,,0000,0000,0000,,with some value
Dialogue: 0,0:14:46.24,0:14:48.20,Default,,0000,0000,0000,,that's called construction
Dialogue: 0,0:14:49.69,0:14:51.54,Default,,0000,0000,0000,,when we're finished, clean up the mess.
Dialogue: 0,0:14:51.96,0:14:56.92,Default,,0000,0000,0000,,if this is a resource handle, this will acquire resources and this will release it.
Dialogue: 0,0:14:57.10,0:15:02.89,Default,,0000,0000,0000,,so, basically there is a clue form about two weak insulate design we've seen in classes long time ago.
Dialogue: 0,0:15:02.93,0:15:06.28,Default,,0000,0000,0000,,a constructor establishes the environment for the members to run in
Dialogue: 0,0:15:06.53,0:15:08.48,Default,,0000,0000,0000,,the destructor reverse its actions.
Dialogue: 0,0:15:08.70,0:15:10.29,Default,,0000,0000,0000,,it's like a pair of pants phrase
Dialogue: 0,0:15:10.29,0:15:14.20,Default,,0000,0000,0000,,because I haven't invent the word constructor and destructor yet.
Dialogue: 0,0:15:14.57,0:15:19.90,Default,,0000,0000,0000,,but, that's where a lot of c++ comes from. right there.
Dialogue: 0,0:15:20.74,0:15:23.05,Default,,0000,0000,0000,,and .. now ..
Dialogue: 0,0:15:23.05,0:15:28.50,Default,,0000,0000,0000,,once we've got classes, eventually we get abstract classes and inheritance.
Dialogue: 0,0:15:28.66,0:15:36.00,Default,,0000,0000,0000,,here's the wey we define a interface that is complete insulate users from the implementation or visa versa.
Dialogue: 0,0:15:36.28,0:15:38.07,Default,,0000,0000,0000,,it has couple of virtual functions that of
Dialogue: 0,0:15:38.12,0:15:39.52,Default,,0000,0000,0000,,pure virtual functions.
Dialogue: 0,0:15:39.84,0:15:43.04,Default,,0000,0000,0000,,there is no data members so it's not a brittle base class
Dialogue: 0,0:15:43.37,0:15:47.36,Default,,0000,0000,0000,,you have to manipulate these things through pointers
Dialogue: 0,0:15:50.64,0:15:54.49,Default,,0000,0000,0000,,and references at least that's what essentially every body does.
Dialogue: 0,0:15:54.89,0:15:57.96,Default,,0000,0000,0000,,and that imply some overhead
Dialogue: 0,0:15:58.26,0:16:01.36,Default,,0000,0000,0000,,and it apply some lifetime management
Dialogue: 0,0:16:01.36,0:16:04.58,Default,,0000,0000,0000,,that can be very messy if you don't think it through.
Dialogue: 0,0:16:04.86,0:16:08.72,Default,,0000,0000,0000,,and you can build these hierarchy base on that.
Dialogue: 0,0:16:09.94,0:16:13.88,Default,,0000,0000,0000,,next, we have parametrized types and classes using templates
Dialogue: 0,0:16:13.88,0:16:16.98,Default,,0000,0000,0000,,that's the essential support for generic programming.
Dialogue: 0,0:16:17.25,0:16:22.02,Default,,0000,0000,0000,,and secondly it allows compile-time computation.
Dialogue: 0,0:16:22.41,0:16:27.16,Default,,0000,0000,0000,,basically you can have a vector that's parametrized by element type
Dialogue: 0,0:16:27.41,0:16:33.52,Default,,0000,0000,0000,,you can and have a sort function that's parametrized by it's container type.
Dialogue: 0,0:16:33.78,0:16:42.04,Default,,0000,0000,0000,,and so we can make a vector of doubles like that, an we can sort some vector with that.
Dialogue: 0,0:16:42.14,0:16:50.44,Default,,0000,0000,0000,,that's the essences of generic programming as represented in c++ and supported
Dialogue: 0,0:16:52.57,0:16:55.94,Default,,0000,0000,0000,,there are some things said and it's not c++
Dialogue: 0,0:16:56.36,0:16:57.93,Default,,0000,0000,0000,,it said it's not everything
Dialogue: 0,0:16:58.80,0:17:08.01,Default,,0000,0000,0000,,some of these things that are really quite fundamental in the design of c++ for good and bad is that no crucial dependence on a garbage collector.
Dialogue: 0,0:17:08.44,0:17:13.89,Default,,0000,0000,0000,,a garbage collector is centralize resources so that's contention for it , in a machine .
Dialogue: 0,0:17:15.01,0:17:17.69,Default,,0000,0000,0000,,I remember the big old time machines
Dialogue: 0,0:17:17.69,0:17:19.69,Default,,0000,0000,0000,,64 processors
Dialogue: 0,0:17:19.69,0:17:20.60,Default,,0000,0000,0000,,real beast
Dialogue: 0,0:17:20.60,0:17:21.45,Default,,0000,0000,0000,,what we do?
Dialogue: 0,0:17:21.75,0:17:24.54,Default,,0000,0000,0000,,63 of them are sit waiting for the garbage collector
Dialogue: 0,0:17:27.59,0:17:30.38,Default,,0000,0000,0000,,c++ is designed not to have this problem
Dialogue: 0,0:17:31.97,0:17:35.29,Default,,0000,0000,0000,,it has other problems in exchange. but this is fundamental issues.
Dialogue: 0,0:17:35.29,0:17:38.29,Default,,0000,0000,0000,,similarly, there is not guarantee type safety.
Dialogue: 0,0:17:39.29,0:17:43.46,Default,,0000,0000,0000,,we did not want it for all constructs
Dialogue: 0,0:17:43.46,0:17:45.01,Default,,0000,0000,0000,,we needed C compatibility
Dialogue: 0,0:17:45.24,0:17:46.40,Default,,0000,0000,0000,,we have history
Dialogue: 0,0:17:47.27,0:17:51.67,Default,,0000,0000,0000,,there are needs to deal with hardware that requires break in the type system
Dialogue: 0,0:17:51.91,0:17:53.26,Default,,0000,0000,0000,,we like to minimize
Dialogue: 0,0:17:53.26,0:17:54.69,Default,,0000,0000,0000,,we like to encapsulated it.
Dialogue: 0,0:17:54.69,0:17:59.85,Default,,0000,0000,0000,,but there was a decision a long time ago that c++ runs on a real machine
Dialogue: 0,0:17:59.85,0:18:03.30,Default,,0000,0000,0000,,it not a mathematical abstraction that it grounds on.
Dialogue: 0,0:18:03.69,0:18:05.59,Default,,0000,0000,0000,,and it no virtual machines
Dialogue: 0,0:18:05.59,0:18:08.11,Default,,0000,0000,0000,,if you wanted to run on a virtual machine
Dialogue: 0,0:18:08.11,0:18:08.80,Default,,0000,0000,0000,,you can
Dialogue: 0,0:18:08.80,0:18:12.99,Default,,0000,0000,0000,,but something has to run on the real machine on the real hardware
Dialogue: 0,0:18:13.38,0:18:15.92,Default,,0000,0000,0000,,for instance the implementation of a virtual machine.
Dialogue: 0,0:18:16.36,0:18:21.31,Default,,0000,0000,0000,,and also there are many domains in which that you can not afford a virtual machine
Dialogue: 0,0:18:21.45,0:18:24.20,Default,,0000,0000,0000,,and you can want to exploit the facilities of the hardware.
Dialogue: 0,0:18:24.49,0:18:29.19,Default,,0000,0000,0000,,if you running in a virtual machine, exploiting a GPU gets rather tricky
Dialogue: 0,0:18:30.29,0:18:37.59,Default,,0000,0000,0000,,if you are on the machine itself , you can go to something that might be type unsafe, that might be an extension, but you can get there.
Dialogue: 0,0:18:39.54,0:18:48.48,Default,,0000,0000,0000,,I have a feel, pictures on these slides, they temped us to do something with c++, so you can wonder what it is.
Dialogue: 0,0:18:48.82,0:18:56.02,Default,,0000,0000,0000,,that, that , there is a distributed computing system with wheels.
Dialogue: 0,0:18:58.30,0:19:05.31,Default,,0000,0000,0000,,there are also things that are not c++ for reasons that are regrettable but they are market realities.
Dialogue: 0,0:19:05.34,0:19:07.21,Default,,0000,0000,0000,,there is no huge standard library
Dialogue: 0,0:19:07.50,0:19:09.33,Default,,0000,0000,0000,,because we don't have a owner
Dialogue: 0,0:19:09.33,0:19:13.54,Default,,0000,0000,0000,,we don't have a sugar dady that can produce free libraries to ensure market share.
Dialogue: 0,0:19:14.09,0:19:16.27,Default,,0000,0000,0000,,we would like to fix that
Dialogue: 0,0:19:16.65,0:19:19.24,Default,,0000,0000,0000,,i'm sure Herb (Herb Sutter) would say something about it
Dialogue: 0,0:19:19.24,0:19:21.97,Default,,0000,0000,0000,,yeah he's got a big screen on this. it's one of his favorite topics.
Dialogue: 0,0:19:22.47,0:19:28.11,Default,,0000,0000,0000,,and, we have no central authorities to approve or reject or help integration of the libraries.
Dialogue: 0,0:19:28.22,0:19:30.70,Default,,0000,0000,0000,,integration of libraries is very difficult.
Dialogue: 0,0:19:31.00,0:19:33.37,Default,,0000,0000,0000,,and we would like to do much better than this.
Dialogue: 0,0:19:33.40,0:19:39.87,Default,,0000,0000,0000,,but for the moment, these are the market realities, this is the way the world have been. for c++ all the time.
Dialogue: 0,0:19:40.09,0:19:48.59,Default,,0000,0000,0000,,so we have no standard GUI library. we have, maybe 25 competing frameworks which is just as bad as none.
Dialogue: 0,0:19:48.59,0:19:52.25,Default,,0000,0000,0000,,awfully , again, it's unfortunate.
Dialogue: 0,0:19:52.56,0:19:56.36,Default,,0000,0000,0000,,we don't have all of these things here standard
Dialogue: 0,0:19:56.36,0:19:57.31,Default,,0000,0000,0000,,they exist
Dialogue: 0,0:19:57.44,0:19:58.54,Default,,0000,0000,0000,,you can pick them up
Dialogue: 0,0:19:58.54,0:19:59.88,Default,,0000,0000,0000,,you can use them today
Dialogue: 0,0:20:00.22,0:20:04.33,Default,,0000,0000,0000,,but they are non-standard. we would like to do better than that.
Dialogue: 0,0:20:04.62,0:20:07.88,Default,,0000,0000,0000,,I don't know if you remember the dragon book
Dialogue: 0,0:20:07.88,0:20:12.75,Default,,0000,0000,0000,,that the knight is slaying dragons on complicity like that.
Dialogue: 0,0:20:13.00,0:20:15.52,Default,,0000,0000,0000,,well, some time the dragon wins.
Dialogue: 0,0:20:16.86,0:20:27.15,Default,,0000,0000,0000,,ok,  going to start on slightly more kicking things. we'll go look at resource management.
Dialogue: 0,0:20:27.90,0:20:36.64,Default,,0000,0000,0000,,basically we have things that we would like to control in system
Dialogue: 0,0:20:36.64,0:20:48.16,Default,,0000,0000,0000,,like memory, the elements of a vector, the characters of a string, the file handles that your operation system provides, threads, locks and things like that.
Dialogue: 0,0:20:48.46,0:20:57.01,Default,,0000,0000,0000,,and basically what we want to do is to have a handle that we used to control access and make it convenient to use these things.
Dialogue: 0,0:20:57.18,0:21:03.62,Default,,0000,0000,0000,,basically , the standard way of using this, is to uses constructor and destructor.
Dialogue: 0,0:21:03.92,0:21:09.05,Default,,0000,0000,0000,,the constructor acquires the resource, here it's memory because it's a vector.
Dialogue: 0,0:21:09.22,0:21:12.60,Default,,0000,0000,0000,,and the destructor, well , gives the memory back again.
Dialogue: 0,0:21:14.48,0:21:15.50,Default,,0000,0000,0000,,so it's very simple
Dialogue: 0,0:21:15.50,0:21:17.08,Default,,0000,0000,0000,,here we have a function
Dialogue: 0,0:21:17.08,0:21:17.92,Default,,0000,0000,0000,,has a vector
Dialogue: 0,0:21:18.16,0:21:19.31,Default,,0000,0000,0000,,it makes a vector
Dialogue: 0,0:21:19.58,0:21:20.66,Default,,0000,0000,0000,,and at the end, when ever we leaves the function, how ever we leave, the destructor cleans up by releasing the memory again.
Dialogue: 0,0:21:20.82,0:21:23.38,Default,,0000,0000,0000,,when ever we leaves the function, how ever we leave it
Dialogue: 0,0:21:23.59,0:21:28.36,Default,,0000,0000,0000,,the destructor cleans up by releasing the memory again.
Dialogue: 0,0:21:29.56,0:21:32.09,Default,,0000,0000,0000,,the basic idea is very very simple
Dialogue: 0,0:21:33.53,0:21:39.40,Default,,0000,0000,0000,,details can be quite heavy depend on the resource, depend on the constraints of the  problems and as such.
Dialogue: 0,0:21:39.78,0:21:44.48,Default,,0000,0000,0000,,but keep that picture in mind. and you can write a lot of good code.
Dialogue: 0,0:21:46.08,0:21:48.09,Default,,0000,0000,0000,,the handle usually is scoped.
Dialogue: 0,0:21:48.25,0:21:55.00,Default,,0000,0000,0000,,as long as the handle is in a scope, and not put on the free store itself , and it's helded by a handle
Dialogue: 0,0:21:55.92,0:21:59.99,Default,,0000,0000,0000,,clean up is automatic and simple
Dialogue: 0,0:22:00.27,0:22:04.94,Default,,0000,0000,0000,,the resource is held for a minimal amount of time
Dialogue: 0,0:22:05.10,0:22:08.02,Default,,0000,0000,0000,,name is scope in which was created.
Dialogue: 0,0:22:08.36,0:22:11.23,Default,,0000,0000,0000,,and basically this is sort of the code here
Dialogue: 0,0:22:11.37,0:22:12.91,Default,,0000,0000,0000,,what the constructor do?
Dialogue: 0,0:22:12.94,0:22:14.65,Default,,0000,0000,0000,,it acquire a resource
Dialogue: 0,0:22:14.95,0:22:19.46,Default,,0000,0000,0000,,set the memory, initialize the memory needed to control things
Dialogue: 0,0:22:19.69,0:22:24.13,Default,,0000,0000,0000,,and possibly does some initialization over what resource has acquired.
Dialogue: 0,0:22:24.52,0:22:27.14,Default,,0000,0000,0000,,and the destructor reverse that
Dialogue: 0,0:22:27.66,0:22:28.28,Default,,0000,0000,0000,,very simple.
Dialogue: 0,0:22:28.70,0:22:29.11,Default,,0000,0000,0000,,so
Dialogue: 0,0:22:30.77,0:22:36.37,Default,,0000,0000,0000,,a resource is anything you acquire and have to release. explicitly or implicitly
Dialogue: 0,0:22:36.37,0:22:37.92,Default,,0000,0000,0000,,that's my definition of resource
Dialogue: 0,0:22:39.26,0:22:40.81,Default,,0000,0000,0000,,and a resource should have a owner
Dialogue: 0,0:22:40.99,0:22:44.92,Default,,0000,0000,0000,,I really dislike stuff that just flat around in the system
Dialogue: 0,0:22:45.27,0:22:46.64,Default,,0000,0000,0000,,and well
Dialogue: 0,0:22:46.98,0:22:50.04,Default,,0000,0000,0000,,people hope some body will take care of them. at some point.
Dialogue: 0,0:22:50.68,0:22:51.76,Default,,0000,0000,0000,,if there is an owner
Dialogue: 0,0:22:51.98,0:22:58.39,Default,,0000,0000,0000,,the owner's job is to make sure the life time is managed, it's initialized up properly and cleaned up properly.
Dialogue: 0,0:22:59.05,0:23:02.75,Default,,0000,0000,0000,,and the ultimate rule for resource is it's scope handle
Dialogue: 0,0:23:03.18,0:23:06.76,Default,,0000,0000,0000,,doesn't have to be scoped, but it's easier if you keep it scoped.
Dialogue: 0,0:23:07.12,0:23:10.66,Default,,0000,0000,0000,,it is also know as Resource Acquisition Is Initialization.
Dialogue: 0,0:23:11.02,0:23:16.48,Default,,0000,0000,0000,,horrible morph. often reduced to RAII.
Dialogue: 0,0:23:16.93,0:23:21.01,Default,,0000,0000,0000,,I can say it's a horrible morph because I invented it and I name it
Dialogue: 0,0:23:21.39,0:23:22.99,Default,,0000,0000,0000,,I should have named it something better
Dialogue: 0,0:23:23.02,0:23:23.21,Default,,0000,0000,0000,,but
Dialogue: 0,0:23:24.24,0:23:24.62,Default,,0000,0000,0000,,well
Dialogue: 0,0:23:24.69,0:23:26.75,Default,,0000,0000,0000,,hand side is relatively easy.
Dialogue: 0,0:23:27.17,0:23:34.23,Default,,0000,0000,0000,,and basically if you failed to acquire your resource
Dialogue: 0,0:23:34.44,0:23:35.54,Default,,0000,0000,0000,,you throw an exception.
Dialogue: 0,0:23:35.69,0:23:39.00,Default,,0000,0000,0000,,it's one of the fundamental reasons that exceptions are in c++.
Dialogue: 0,0:23:39.26,0:23:43.67,Default,,0000,0000,0000,,it is that has to be a way of getting out of a task that you have been ask to do
Dialogue: 0,0:23:43.90,0:23:44.72,Default,,0000,0000,0000,,and can't do
Dialogue: 0,0:23:44.80,0:23:47.68,Default,,0000,0000,0000,,like constructor can't construct its object
Dialogue: 0,0:23:47.95,0:23:49.62,Default,,0000,0000,0000,,it has to be able to get out of there
Dialogue: 0,0:23:50.00,0:23:52.94,Default,,0000,0000,0000,,if you don't have exceptions you have to fake them.
Dialogue: 0,0:23:53.45,0:23:54.09,Default,,0000,0000,0000,,em
Dialogue: 0,0:23:54.32,0:23:55.88,Default,,0000,0000,0000,,you try to construct an object, but the object
Dialogue: 0,0:23:55.94,0:23:57.74,Default,,0000,0000,0000,,but the object  are set in a bad state
Dialogue: 0,0:23:57.77,0:23:59.56,Default,,0000,0000,0000,,and you have to test validate
Dialogue: 0,0:23:59.95,0:24:01.09,Default,,0000,0000,0000,,something like that
Dialogue: 0,0:24:01.17,0:24:02.27,Default,,0000,0000,0000,,pretty horrible stuff
Dialogue: 0,0:24:02.90,0:24:04.96,Default,,0000,0000,0000,,and basically
Dialogue: 0,0:24:05.21,0:24:07.88,Default,,0000,0000,0000,,the rules for not leaking becomes
Dialogue: 0,0:24:08.33,0:24:13.71,Default,,0000,0000,0000,,never throw while holding a resource that's not own by a handle
Dialogue: 0,0:24:14.13,0:24:14.40,Default,,0000,0000,0000,,so
Dialogue: 0,0:24:14.58,0:24:16.15,Default,,0000,0000,0000,,if you do something silly
Dialogue: 0,0:24:16.33,0:24:21.84,Default,,0000,0000,0000,,like acquire some memory, and hold an pointer to it
Dialogue: 0,0:24:21.97,0:24:24.22,Default,,0000,0000,0000,,and throw exception, you're are in deep trouble
Dialogue: 0,0:24:24.50,0:24:25.73,Default,,0000,0000,0000,,we'll get back to that.
Dialogue: 0,0:24:26.80,0:24:28.80,Default,,0000,0000,0000,,ok
Dialogue: 0,0:24:28.80,0:24:30.53,Default,,0000,0000,0000,,here is an example
Dialogue: 0,0:24:30.81,0:24:31.89,Default,,0000,0000,0000,,we have a mutex
Dialogue: 0,0:24:32.10,0:24:33.92,Default,,0000,0000,0000,,it's a system resource
Dialogue: 0,0:24:34.29,0:24:36.34,Default,,0000,0000,0000,,and..
Dialogue: 0,0:24:37.29,0:24:38.02,Default,,0000,0000,0000,,sorry
Dialogue: 0,0:24:38.92,0:24:42.37,Default,,0000,0000,0000,,we have something we want to share, which is a shared data here
Dialogue: 0,0:24:42.61,0:24:44.86,Default,,0000,0000,0000,,and we want to controlle it by a mutex.
Dialogue: 0,0:24:45.08,0:24:51.05,Default,,0000,0000,0000,,mutex is an standard system resource, and it it represented in the standard library by the mutex class
Dialogue: 0,0:24:51.14,0:24:55.44,Default,,0000,0000,0000,,and the mutex class is actually a handle to the system resource
Dialogue: 0,0:24:55.64,0:24:56.29,Default,,0000,0000,0000,,and so ...
Dialogue: 0,0:24:56.66,0:24:57.44,Default,,0000,0000,0000,,what ... er ...
Dialogue: 0,0:24:58.16,0:24:59.02,Default,,0000,0000,0000,,system resource...
Dialogue: 0,0:24:59.05,0:24:59.53,Default,,0000,0000,0000,,yeah
Dialogue: 0,0:24:59.96,0:25:00.78,Default,,0000,0000,0000,,just think about that
Dialogue: 0,0:25:00.78,0:25:01.80,Default,,0000,0000,0000,,it is a system resource
Dialogue: 0,0:25:02.13,0:25:03.20,Default,,0000,0000,0000,,we going to a scope
Dialogue: 0,0:25:03.69,0:25:04.67,Default,,0000,0000,0000,,we take a lock on it.
Dialogue: 0,0:25:04.90,0:25:09.19,Default,,0000,0000,0000,,that is the local object that hold the mutex.
Dialogue: 0,0:25:09.56,0:25:10.60,Default,,0000,0000,0000,,use the data
Dialogue: 0,0:25:10.75,0:25:12.57,Default,,0000,0000,0000,,and we go out of there.
Dialogue: 0,0:25:12.88,0:25:14.77,Default,,0000,0000,0000,,we don't care how we go out of there.
Dialogue: 0,0:25:14.97,0:25:17.23,Default,,0000,0000,0000,,now this is of course the overly simplified
Dialogue: 0,0:25:17.23,0:25:17.53,Default,,0000,0000,0000,,we don't ...
Dialogue: 0,0:25:20.13,0:25:24.46,Default,,0000,0000,0000,,we often have more code working in that critical region just there
Dialogue: 0,0:25:24.77,0:25:26.81,Default,,0000,0000,0000,,so we can goes out of there by
Dialogue: 0,0:25:26.94,0:25:27.70,Default,,0000,0000,0000,,returnning
Dialogue: 0,0:25:27.70,0:25:29.94,Default,,0000,0000,0000,,by falling off the scope
Dialogue: 0,0:25:30.02,0:25:31.47,Default,,0000,0000,0000,,or by throwing an exception
Dialogue: 0,0:25:31.73,0:25:33.53,Default,,0000,0000,0000,,but with all of these cases
Dialogue: 0,0:25:33.92,0:25:35.68,Default,,0000,0000,0000,,the lock guard
Dialogue: 0,0:25:35.89,0:25:37.53,Default,,0000,0000,0000,,will release the resource\
Dialogue: 0,0:25:37.66,0:25:38.61,Default,,0000,0000,0000,,that's the main point.
Dialogue: 0,0:25:39.09,0:25:42.24,Default,,0000,0000,0000,,acquire --  use  -- release
Dialogue: 0,0:25:43.55,0:25:44.03,Default,,0000,0000,0000,,so
Dialogue: 0,0:25:44.18,0:25:48.19,Default,,0000,0000,0000,,here is an example of
Dialogue: 0,0:25:50.77,0:25:55.11,Default,,0000,0000,0000,,what code I found when I look around that I think is pretty awful.
Dialogue: 0,0:25:55.78,0:25:58.10,Default,,0000,0000,0000,,it's not just written by java programmers
Dialogue: 0,0:25:58.16,0:26:03.45,Default,,0000,0000,0000,,but it's just getting more common that it used to be.
Dialogue: 0,0:26:03.93,0:26:07.93,Default,,0000,0000,0000,,there is always people writing code like the screen here
Dialogue: 0,0:26:08.26,0:26:11.17,Default,,0000,0000,0000,,but unfortunately this is an increasingly problem.
Dialogue: 0,0:26:11.38,0:26:11.83,Default,,0000,0000,0000,,so
Dialogue: 0,0:26:12.11,0:26:13.85,Default,,0000,0000,0000,,I ... get a gadget
Dialogue: 0,0:26:13.85,0:26:15.41,Default,,0000,0000,0000,,get it on the free store
Dialogue: 0,0:26:15.41,0:26:17.32,Default,,0000,0000,0000,,I learned  object oriented programming
Dialogue: 0,0:26:17.51,0:26:19.58,Default,,0000,0000,0000,,every thing has to be on the free store
Dialogue: 0,0:26:19.59,0:26:21.18,Default,,0000,0000,0000,,I manipulate it through pointers
Dialogue: 0,0:26:21.35,0:26:22.55,Default,,0000,0000,0000,,so that's what I'm doing.
Dialogue: 0,0:26:22.83,0:26:23.66,Default,,0000,0000,0000,,then I go down
Dialogue: 0,0:26:23.66,0:26:24.91,Default,,0000,0000,0000,,I may throw an exception
Dialogue: 0,0:26:25.36,0:26:27.27,Default,,0000,0000,0000,,and I ...
Dialogue: 0,0:26:28.10,0:26:30.24,Default,,0000,0000,0000,,some one might say why exceptions are bad
Dialogue: 0,0:26:30.27,0:26:32.30,Default,,0000,0000,0000,,because I may leak the gadget. '
Dialogue: 0,0:26:32.70,0:26:35.00,Default,,0000,0000,0000,,No, I'm saying you did something else wrong
Dialogue: 0,0:26:35.05,0:26:37.40,Default,,0000,0000,0000,,because you can get the same problem just from returning.
Dialogue: 0,0:26:38.28,0:26:39.24,Default,,0000,0000,0000,,in other words
Dialogue: 0,0:26:39.68,0:26:44.09,Default,,0000,0000,0000,,i have this gadget here  that i have acquired I have to delete it
Dialogue: 0,0:26:44.40,0:26:49.37,Default,,0000,0000,0000,,and some how that puts major constraint on what I can write in the function.
Dialogue: 0,0:26:49.64,0:26:52.84,Default,,0000,0000,0000,,in particular, I mustn't leave without deleting p
Dialogue: 0,0:26:53.93,0:26:56.19,Default,,0000,0000,0000,,and people then say they want the garbage collector
Dialogue: 0,0:26:56.44,0:26:57.09,Default,,0000,0000,0000,,which you known
Dialogue: 0,0:26:57.28,0:26:59.51,Default,,0000,0000,0000,,I didn't tell you what is inside the gadget
Dialogue: 0,0:27:00.17,0:27:02.71,Default,,0000,0000,0000,,if that's just memory, a garbage collector will help you.
Dialogue: 0,0:27:03.43,0:27:04.96,Default,,0000,0000,0000,,if it's a file handle
Dialogue: 0,0:27:05.33,0:27:06.17,Default,,0000,0000,0000,,a socket
Dialogue: 0,0:27:06.85,0:27:07.63,Default,,0000,0000,0000,,and a lock
Dialogue: 0,0:27:09.04,0:27:09.80,Default,,0000,0000,0000,,err....
Dialogue: 0,0:27:10.15,0:27:11.92,Default,,0000,0000,0000,,the garbage collector will not help you.
Dialogue: 0,0:27:12.17,0:27:12.48,Default,,0000,0000,0000,,so
Dialogue: 0,0:27:12.56,0:27:13.86,Default,,0000,0000,0000,,this code is bad.
Dialogue: 0,0:27:13.86,0:27:14.99,Default,,0000,0000,0000,,if I throw here
Dialogue: 0,0:27:15.37,0:27:18.04,Default,,0000,0000,0000,,I have leak the gadget, and gadget holds a lot of thing.
Dialogue: 0,0:27:19.55,0:27:21.33,Default,,0000,0000,0000,,so, naked pointers are bad.
Dialogue: 0,0:27:21.64,0:27:23.25,Default,,0000,0000,0000,,because they are hard to manage.
Dialogue: 0,0:27:23.25,0:27:25.59,Default,,0000,0000,0000,,so people say, let's use a share pointer.
Dialogue: 0,0:27:25.96,0:27:29.70,Default,,0000,0000,0000,,a share pointer is one of these handles, they hold a  pointer
Dialogue: 0,0:27:30.51,0:27:43.14,Default,,0000,0000,0000,,and when you acquire a pointer, It holds it. and if you goes out of the scope, the share pointer will release the resource
Dialogue: 0,0:27:43.17,0:27:47.38,Default,,0000,0000,0000,,if it io the last one, that holds it
Dialogue: 0,0:27:48.10,0:27:48.92,Default,,0000,0000,0000,,in other words
Dialogue: 0,0:27:49.01,0:27:51.17,Default,,0000,0000,0000,,a share pointer is a form of garbage collection.
Dialogue: 0,0:27:51.87,0:27:53.17,Default,,0000,0000,0000,,If i have a share pointer
Dialogue: 0,0:27:53.48,0:27:55.84,Default,,0000,0000,0000,,I give you a copy, i give you a copy
Dialogue: 0,0:27:56.13,0:28:02.22,Default,,0000,0000,0000,,and the last one of us that gives up the copy , will destroy the object.\Nthat's the idea of share pointer.
Dialogue: 0,0:28:04.61,0:28:05.31,Default,,0000,0000,0000,,but you know
Dialogue: 0,0:28:05.61,0:28:08.25,Default,,0000,0000,0000,,i'm not actually share anything with anybody here
Dialogue: 0,0:28:08.55,0:28:10.54,Default,,0000,0000,0000,,that gadget is mine on mine.
Dialogue: 0,0:28:11.50,0:28:12.09,Default,,0000,0000,0000,,and so
Dialogue: 0,0:28:12.49,0:28:15.18,Default,,0000,0000,0000,,why am i dealing with garbage collection here?
Dialogue: 0,0:28:15.18,0:28:18.25,Default,,0000,0000,0000,,even the shared pointer version of garbage collection
Dialogue: 0,0:28:18.68,0:28:21.36,Default,,0000,0000,0000,,if you people think I misused the word garbage collection
Dialogue: 0,0:28:21.58,0:28:28.16,Default,,0000,0000,0000,,remember that original garbage collection is defined by share pointer, counted pointers.
Dialogue: 0,0:28:28.60,0:28:34.43,Default,,0000,0000,0000,,and because the language calles them self garbage collected, because every thing is a shared pointer.
Dialogue: 0,0:28:35.71,0:28:37.20,Default,,0000,0000,0000,,this is a form of garbage collection.
Dialogue: 0,0:28:37.51,0:28:42.39,Default,,0000,0000,0000,,but , you know, that the use count for the gadget goes from 0 to 1
Dialogue: 0,0:28:42.97,0:28:45.94,Default,,0000,0000,0000,,and eventualy from 1 to 0 , which is what it does
Dialogue: 0,0:28:47.07,0:28:48.25,Default,,0000,0000,0000,,I'm not sharing anything.
Dialogue: 0,0:28:48.32,0:28:50.66,Default,,0000,0000,0000,,there is standard library unique pointer
Dialogue: 0,0:28:51.08,0:28:54.12,Default,,0000,0000,0000,,that would allow me to say just hold on this one
Dialogue: 0,0:28:55.27,0:28:57.91,Default,,0000,0000,0000,,destroy it if i leave this scope
Dialogue: 0,0:28:58.08,0:29:04.38,Default,,0000,0000,0000,,when I leave the scope,  that's all , that's unique pointer. don't share with any body, that's fine.
Dialogue: 0,0:29:04.70,0:29:05.21,Default,,0000,0000,0000,,but, do you know?
Dialogue: 0,0:29:06.86,0:29:08.64,Default,,0000,0000,0000,,why am I dealing with pointers here?
Dialogue: 0,0:29:10.01,0:29:13.12,Default,,0000,0000,0000,,actually the code I would like to become common and ??
Dialogue: 0,0:29:13.38,0:29:14.07,Default,,0000,0000,0000,,is actually like this
Dialogue: 0,0:29:14.07,0:29:15.12,Default,,0000,0000,0000,,I make an gadget
Dialogue: 0,0:29:15.79,0:29:17.05,Default,,0000,0000,0000,,what should the gadget be ?
Dialogue: 0,0:29:17.24,0:29:23.02,Default,,0000,0000,0000,,a gedget should be nice thing. if it hold some thing, it would be an handle to what it holds
Dialogue: 0,0:29:23.34,0:29:32.14,Default,,0000,0000,0000,,if is a file handle in it , the constructor will initialize the file handle and the destructor will close the file again.
Dialogue: 0,0:29:32.54,0:29:36.06,Default,,0000,0000,0000,,if it has a lock, it will do locks unlocks as needed,
Dialogue: 0,0:29:36.36,0:29:39.94,Default,,0000,0000,0000,,if owns a memory, it will acquire memory on construct and release the memory in destructor.
Dialogue: 0,0:29:40.25,0:29:46.82,Default,,0000,0000,0000,,all of those automatic is gadget's job to maintain the gadget's resource. right ?
Dialogue: 0,0:29:47.48,0:29:48.07,Default,,0000,0000,0000,,I mean
Dialogue: 0,0:29:48.14,0:29:50.50,Default,,0000,0000,0000,,i have an abstraction should be proper abstract
Dialogue: 0,0:29:50.50,0:29:52.87,Default,,0000,0000,0000,,these should be no longer a problem.
Dialogue: 0,0:29:53.32,0:29:56.77,Default,,0000,0000,0000,,because the destructor for the gadget, will take care of it.
Dialogue: 0,0:29:57.39,0:29:58.75,Default,,0000,0000,0000,,and some, things are simple.
Dialogue: 0,0:29:59.09,0:30:02.92,Default,,0000,0000,0000,,I really like it when you take some complicated code like that
Dialogue: 0,0:30:03.58,0:30:04.69,Default,,0000,0000,0000,,and improve it
Dialogue: 0,0:30:05.77,0:30:07.73,Default,,0000,0000,0000,,by make it much more simpler.
Dialogue: 0,0:30:08.21,0:30:11.41,Default,,0000,0000,0000,,that's the idea. we want to have simple things simple.
Dialogue: 0,0:30:11.92,0:30:19.82,Default,,0000,0000,0000,,there are things can not do, with just RAII model. there are complicated data structures that require more thought
Dialogue: 0,0:30:20.08,0:30:23.31,Default,,0000,0000,0000,,there are places where you require share pointer etc, etc.
Dialogue: 0,0:30:23.65,0:30:25.32,Default,,0000,0000,0000,,but simple things should be simple.
Dialogue: 0,0:30:25.60,0:30:27.00,Default,,0000,0000,0000,,and this is am example of it.
Dialogue: 0,0:30:28.10,0:30:30.16,Default,,0000,0000,0000,,so, what do we actually use pointers for?
Dialogue: 0,0:30:30.66,0:30:34.80,Default,,0000,0000,0000,,if i'm saying, pointers should not represent ownership.
Dialogue: 0,0:30:35.85,0:30:38.69,Default,,0000,0000,0000,,handles represent ownership
Dialogue: 0,0:30:39.03,0:30:42.69,Default,,0000,0000,0000,,and pointers live inside handler, and are used by them
Dialogue: 0,0:30:43.21,0:30:46.97,Default,,0000,0000,0000,,also, you represent resource inside a handle.
Dialogue: 0,0:30:47.35,0:30:49.08,Default,,0000,0000,0000,,you represent positions.
Dialogue: 0,0:30:49.18,0:30:50.27,Default,,0000,0000,0000,,so that's why we have .... ..
Dialogue: 0,0:30:52.52,0:30:55.57,Default,,0000,0000,0000,,pointers into arrays  like we use indexes.
Dialogue: 0,0:30:55.71,0:31:00.54,Default,,0000,0000,0000,,and we have iterators, all of these god stuff which are pointers in disguise
Dialogue: 0,0:31:00.76,0:31:01.76,Default,,0000,0000,0000,,by and large
Dialogue: 0,0:31:01.76,0:31:08.06,Default,,0000,0000,0000,,represent positions we have to be careful, we can have range checking.
Dialogue: 0,0:31:08.61,0:31:12.26,Default,,0000,0000,0000,,they (pointers) are really good to pass in large amount of data around.
Dialogue: 0,0:31:12.49,0:31:15.85,Default,,0000,0000,0000,,usually in the form of reference or const reference.
Dialogue: 0,0:31:16.13,0:31:21.15,Default,,0000,0000,0000,,that's how we get to say two matries into a add function
Dialogue: 0,0:31:21.16,0:31:23.37,Default,,0000,0000,0000,,for matrices, we pass const references.
Dialogue: 0,0:31:23.74,0:31:28.29,Default,,0000,0000,0000,,pointers in various guises  are really good thing to pass things to others.
Dialogue: 0,0:31:30.01,0:31:35.95,Default,,0000,0000,0000,,people use pointers to pass things out of functions' results
Dialogue: 0,0:31:36.62,0:31:41.34,Default,,0000,0000,0000,,and I'm going to show alternative to that.
Dialogue: 0,0:31:42.23,0:31:43.93,Default,,0000,0000,0000,,so here is the problem
Dialogue: 0,0:31:45.73,0:31:54.13,Default,,0000,0000,0000,,we can get informations, representatives inside functions, we can get informations into functions, but how do we get it out again?
Dialogue: 0,0:31:55.73,0:31:58.90,Default,,0000,0000,0000,,the idea of getting things out of a function
Dialogue: 0,0:31:59.64,0:32:03.23,Default,,0000,0000,0000,,usually if it's a lot of data
Dialogue: 0,0:32:03.53,0:32:05.19,Default,,0000,0000,0000,,or if it is a complicated object
Dialogue: 0,0:32:05.39,0:32:13.07,Default,,0000,0000,0000,,we put it on the free store, and return a pointer to the object we put on the free store
Dialogue: 0,0:32:13.20,0:32:19.15,Default,,0000,0000,0000,,the problem is, we use "new" to get things on free store, so who delete?
Dialogue: 0,0:32:20.16,0:32:28.90,Default,,0000,0000,0000,,is the operation that create the object? or the code that call the object?
Dialogue: 0,0:32:29.30,0:32:34.52,Default,,0000,0000,0000,,neither of those solutions are ideal
Dialogue: 0,0:32:35.23,0:32:38.05,Default,,0000,0000,0000,,neither of those solutions are un-manageable
Dialogue: 0,0:32:38.51,0:32:44.67,Default,,0000,0000,0000,,but a lot of the un-manageable resource management using a lot of pointers. has a root in these problems.
Dialogue: 0,0:32:44.76,0:32:48.30,Default,,0000,0000,0000,,people don't decide who owns what and who cleans what
Dialogue: 0,0:32:48.72,0:32:51.81,Default,,0000,0000,0000,,so things pass to an interface, and disappear
Dialogue: 0,0:32:52.67,0:32:56.61,Default,,0000,0000,0000,,we can try and solve by references. that's even worse.
Dialogue: 0,0:32:57.07,0:33:01.52,Default,,0000,0000,0000,,because I return some reference to something that's on the free store
Dialogue: 0,0:33:02.17,0:33:04.17,Default,,0000,0000,0000,,omebody still has to leak the pointer.
Dialogue: 0,0:33:04.31,0:33:08.35,Default,,0000,0000,0000,,and the obverse question is, what pointer? I don't see any pointer.
Dialogue: 0,0:33:08.73,0:33:16.54,Default,,0000,0000,0000,,A reference looks -- when used -- use like an object. and you have disguise the problem rather that solve it.
Dialogue: 0,0:33:17.12,0:33:19.24,Default,,0000,0000,0000,,we can pass a target object
Dialogue: 0,0:33:19.63,0:33:22.93,Default,,0000,0000,0000,,so instead of adding two matrices and returning a result
Dialogue: 0,0:33:23.43,0:33:28.40,Default,,0000,0000,0000,,we can say add(a,b,c);
Dialogue: 0,0:33:28.40,0:33:32.99,Default,,0000,0000,0000,,it takes a + b and put the result to what ever c points to.
Dialogue: 0,0:33:33.53,0:33:35.69,Default,,0000,0000,0000,,that's a popular way of doing it.
Dialogue: 0,0:33:35.90,0:33:38.59,Default,,0000,0000,0000,,the problem is where it regress towards simply code.
Dialogue: 0,0:33:39.07,0:33:45.31,Default,,0000,0000,0000,,and output parameters is one of sources to complex and confusion.
Dialogue: 0,0:33:45.68,0:33:51.39,Default,,0000,0000,0000,,when I say  plus(a,b,c), what does that mean?
Dialogue: 0,0:33:51.58,0:33:53.14,Default,,0000,0000,0000,,I have to read the documentation.
Dialogue: 0,0:33:53.62,0:33:59.43,Default,,0000,0000,0000,,at least we have const, so that we can tell which one is suppose to be inputs and which one is not.
Dialogue: 0,0:33:59.86,0:34:03.96,Default,,0000,0000,0000,,but if people are not consistent and they just look at the code.
Dialogue: 0,0:34:05.60,0:34:06.66,Default,,0000,0000,0000,,what's what ?
Dialogue: 0,0:34:06.92,0:34:08.16,Default,,0000,0000,0000,,this is source of bugs.
Dialogue: 0,0:34:08.39,0:34:13.56,Default,,0000,0000,0000,,\Nsimilarly, the code before hand just looks like a becomes b + c
Dialogue: 0,0:34:13.81,0:34:19.67,Default,,0000,0000,0000,,now looks declare some result type c, and then plus a become b become c
Dialogue: 0,0:34:19.67,0:34:22.93,Default,,0000,0000,0000,,that some time it doubles the amount of code you have to write.
Dialogue: 0,0:34:22.93,0:34:24.67,Default,,0000,0000,0000,,I don't like the solution
Dialogue: 0,0:34:24.82,0:34:27.09,Default,,0000,0000,0000,,it works, some time it's the best we can do.
Dialogue: 0,0:34:27.24,0:34:28.38,Default,,0000,0000,0000,,but we are regression
Dialogue: 0,0:34:28.38,0:34:33.45,Default,,0000,0000,0000,,we throwing away few hundred years of progress in notation.
Dialogue: 0,0:34:34.27,0:34:38.33,Default,,0000,0000,0000,,and we can return an object. when we try that, that works nice.
Dialogue: 0,0:34:38.33,0:34:43.11,Default,,0000,0000,0000,,if the object we are returning is an integer, or complex number (: std::complex<>）that's not a problem.
Dialogue: 0,0:34:43.58,0:34:49.85,Default,,0000,0000,0000,,if it is a matrix of a million elements, even a modern process can ... can feel the pain
Dialogue: 0,0:34:50.37,0:34:57.45,Default,,0000,0000,0000,,and so, copies can be expensive, and then we start eventing tricks for returning objects cheaply.
Dialogue: 0,0:34:57.81,0:34:58.39,Default,,0000,0000,0000,,well
Dialogue: 0,0:34:58.44,0:35:06.74,Default,,0000,0000,0000,,that sort of works in the hand of competence programmer in a code base strictly controlled by somebody knows well  doing it works
Dialogue: 0,0:35:07.08,0:35:09.19,Default,,0000,0000,0000,,but in this area here
Dialogue: 0,0:35:09.23,0:35:20.65,Default,,0000,0000,0000,,is where we found a lot of the awful code that, for not solving this problem permanence a million line  code base and become sources of problems.
Dialogue: 0,0:35:20.91,0:35:21.34,Default,,0000,0000,0000,,
Dialogue: 0,0:35:21.72,0:35:24.24,Default,,0000,0000,0000,,we can return a handle
Dialogue: 0,0:35:24.72,0:35:31.21,Default,,0000,0000,0000,,don't return the elements of the matrix, don't return pointer to the elements
Dialogue: 0,0:35:31.30,0:35:33.38,Default,,0000,0000,0000,,return the matrix which is the handle
Dialogue: 0,0:35:34.25,0:35:36.10,Default,,0000,0000,0000,,ok, so, how do we do this.
Dialogue: 0,0:35:36.25,0:35:36.65,Default,,0000,0000,0000,,here,
Dialogue: 0,0:35:36.81,0:35:38.50,Default,,0000,0000,0000,,this is what the way we want the code to work.
Dialogue: 0,0:35:39.09,0:35:45.30,Default,,0000,0000,0000,,i want a matrix that takes two .. (BS纠正口误)... plus operation that takes two inputs and produces the result.
Dialogue: 0,0:35:45.31,0:35:47.75,Default,,0000,0000,0000,,I want to do that by making up a local variable
Dialogue: 0,0:35:48.12,0:35:54.53,Default,,0000,0000,0000,,I want to fill it up with the good stuff i want to get out. and I want to return it.\Nand I write my code like this.
Dialogue: 0,0:35:54.90,0:35:55.46,Default,,0000,0000,0000,,and
Dialogue: 0,0:35:55.65,0:35:57.35,Default,,0000,0000,0000,,this , this works nicely.
Dialogue: 0,0:35:57.96,0:36:01.29,Default,,0000,0000,0000,,n here, "r" is a handle to all the elements
Dialogue: 0,0:36:01.71,0:36:03.88,Default,,0000,0000,0000,,and the return operation is simply
Dialogue: 0,0:36:04.35,0:36:06.77,Default,,0000,0000,0000,,take that point there and give it "res".
Dialogue: 0,0:36:07.52,0:36:15.11,Default,,0000,0000,0000,,and then put a nullptr in its place. that's know as move operation.
Dialogue: 0,0:36:15.33,0:36:17.29,Default,,0000,0000,0000,,even little kids can understand this
Dialogue: 0,0:36:17.29,0:36:17.64,Default,,0000,0000,0000,,look！
Dialogue: 0,0:36:17.64,0:36:21.35,Default,,0000,0000,0000,,here is an object right, I moved it over here.  it not here.
Dialogue: 0,0:36:22.42,0:36:29.83,Default,,0000,0000,0000,,ok. only a computer scientist would make a copy, move the copy over here, and destroy the original.
Dialogue: 0,0:36:30.76,0:36:34.23,Default,,0000,0000,0000,,You actually need a degree to figure that one out.
Dialogue: 0,0:36:34.69,0:36:37.96,Default,,0000,0000,0000,,little kids at about 8 - 6 month can do this.
Dialogue: 0,0:36:38.71,0:36:44.92,Default,,0000,0000,0000,,ok, that does it look like in code？
Dialogue: 0,0:36:45.29,0:36:49.75,Default,,0000,0000,0000,,this is a funny notation, that this one is a move constructor.
Dialogue: 0,0:36:50.12,0:36:55.35,Default,,0000,0000,0000,,a move constructor is called from some thing that we don't need any more.
Dialogue: 0,0:36:55.75,0:36:57.75,Default,,0000,0000,0000,,like the source of a return statement.
Dialogue: 0,0:36:58.04,0:37:00.69,Default,,0000,0000,0000,,and it does exactly this as I said.
Dialogue: 0,0:37:01.07,0:37:05.31,Default,,0000,0000,0000,,here, it copies the representation and zeros out the representation.
Dialogue: 0,0:37:05.66,0:37:06.32,Default,,0000,0000,0000,,
Dialogue: 0,0:37:06.81,0:37:14.60,Default,,0000,0000,0000,,it copies because that's what hardware does well for small things like a pointer, or integer.
Dialogue: 0,0:37:14.60,0:37:17.11,Default,,0000,0000,0000,,and the matrix simply is just integer
Dialogue: 0,0:37:17.34,0:37:25.94,Default,,0000,0000,0000,,it may be ... a pointer ...  and it may be a pointer and a couple of dimensions -- its small.
Dialogue: 0,0:37:26.25,0:37:27.08,Default,,0000,0000,0000,,so
Dialogue: 0,0:37:27.22,0:37:27.51,Default,,0000,0000,0000,,we...
Dialogue: 0,0:37:27.54,0:37:34.76,Default,,0000,0000,0000,,this operation here, the move operation is .. is something that is really cheep.
Dialogue: 0,0:37:34.76,0:37:44.59,Default,,0000,0000,0000,,so if you want to move a million elements matrix out of an operation, it cost two DWORD assignment. that that's affordable.
Dialogue: 0,0:37:45.24,0:37:46.16,Default,,0000,0000,0000,,ok
Dialogue: 0,0:37:46.27,0:37:47.80,Default,,0000,0000,0000,,so .. errr.
Dialogue: 0,0:37:49.63,0:37:59.10,Default,,0000,0000,0000,,this leads me to the conclusion that no garbage collection is needed for this simple implicit and efficient resource management
Dialogue: 0,0:37:59.10,0:38:00.03,Default,,0000,0000,0000,,we can do that
Dialogue: 0,0:38:00.35,0:38:02.43,Default,,0000,0000,0000,,and so , we had a set of techniques
Dialogue: 0,0:38:02.91,0:38:05.29,Default,,0000,0000,0000,,fist we store data in containers
Dialogue: 0,0:38:05.49,0:38:09.52,Default,,0000,0000,0000,,and they should reflect the fundamental abstraction in their interface
Dialogue: 0,0:38:09.72,0:38:11.69,Default,,0000,0000,0000,,and they handles lifetime management.
Dialogue: 0,0:38:12.04,0:38:17.33,Default,,0000,0000,0000,,and you handle all resources with resource handle. not just memory
Dialogue: 0,0:38:17.72,0:38:24.42,Default,,0000,0000,0000,,this is important. I don't want to leak sockets. I don't want to leak file handles, etc etc etc.
Dialogue: 0,0:38:24.67,0:38:28.11,Default,,0000,0000,0000,,your system have a lot of resources. some of which I never heard of
Dialogue: 0,0:38:28.48,0:38:32.86,Default,,0000,0000,0000,,they are just something in your system, has to be acquired and released.
Dialogue: 0,0:38:33.00,0:38:35.57,Default,,0000,0000,0000,,that's resource, all of those have to be managed.
Dialogue: 0,0:38:37.05,0:38:41.43,Default,,0000,0000,0000,,if you can't get this working, you can start using smart pointers
Dialogue: 0,0:38:41.43,0:38:45.01,Default,,0000,0000,0000,,unique pointers are very good at holding things to scopes
Dialogue: 0,0:38:45.20,0:38:50.57,Default,,0000,0000,0000,,they are also very good at hold unique ownership, hand unique ownership over to somebody else.
Dialogue: 0,0:38:50.91,0:38:58.97,Default,,0000,0000,0000,,share pointers for the case is  where you can't work out the ownership, it is really uncertain who is the last user.
Dialogue: 0,0:38:59.30,0:39:05.82,Default,,0000,0000,0000,,try not to get there, but when you get there, smart pointers share pointers will do the job.
Dialogue: 0,0:39:06.26,0:39:09.03,Default,,0000,0000,0000,,and finally , if you have gotten yourself into a mess -
Dialogue: 0,0:39:09.69,0:39:12.39,Default,,0000,0000,0000,,which a lot of us has - especially with old code
Dialogue: 0,0:39:12.39,0:39:13.71,Default,,0000,0000,0000,,lots of pointers
Dialogue: 0,0:39:13.71,0:39:15.94,Default,,0000,0000,0000,,no real understanding  of who owns what
Dialogue: 0,0:39:15.94,0:39:25.94,Default,,0000,0000,0000,,no really clearly actual clearly set of rules for error handling and resource management
Dialogue: 0,0:39:26.30,0:39:27.56,Default,,0000,0000,0000,,this is not uncommon
Dialogue: 0,0:39:27.69,0:39:31.54,Default,,0000,0000,0000,,or if there is is some clearly apically rules that may not be followed
Dialogue: 0,0:39:31.70,0:39:34.05,Default,,0000,0000,0000,,in that case, you can plug-in a garbage collector.
Dialogue: 0,0:39:34.42,0:39:36.65,Default,,0000,0000,0000,,and get what's known as litter collection.
Dialogue: 0,0:39:36.65,0:39:41.60,Default,,0000,0000,0000,,their shouldn't be much garbage . because we already built with  most of there
Dialogue: 0,0:39:41.65,0:39:43.85,Default,,0000,0000,0000,,so it's relatively cheep.
Dialogue: 0,0:39:44.03,0:39:47.29,Default,,0000,0000,0000,,c++11 specifics an interface for this
Dialogue: 0,0:39:50.76,0:39:53.87,Default,,0000,0000,0000,,it can still leak non memory resources
Dialogue: 0,0:39:54.10,0:39:58.59,Default,,0000,0000,0000,,i can be efficient and effective , and you can go if you want to.
Dialogue: 0,0:39:58.85,0:40:06.62,Default,,0000,0000,0000,,but the point is , the usual order of preference has be reverse here.
Dialogue: 0,0:40:07.04,0:40:09.93,Default,,0000,0000,0000,,it is not the idea is garbage collection
Dialogue: 0,0:40:10.00,0:40:13.08,Default,,0000,0000,0000,,and if you don't have garbage collection, we will do something else, no.
Dialogue: 0,0:40:13.43,0:40:16.39,Default,,0000,0000,0000,,the idea is perfect resource safety.
Dialogue: 0,0:40:16.70,0:40:22.06,Default,,0000,0000,0000,,with minimal overheads and minimal resource retention times
Dialogue: 0,0:40:22.44,0:40:30.32,Default,,0000,0000,0000,,and then eventually if everything else fails , we can plug-in an garbage collector. at this point, garbage collection becomes cheep.
Dialogue: 0,0:40:30.89,0:40:33.15,Default,,0000,0000,0000,,so, em...
Dialogue: 0,0:40:35.59,0:40:39.57,Default,,0000,0000,0000,,I sort of uncomfortable when I don't show code for awhile.
Dialogue: 0,0:40:39.89,0:40:45.68,Default,,0000,0000,0000,,so let me show a little bit some of the facilities we had in c++11
Dialogue: 0,0:40:45.95,0:40:49.04,Default,,0000,0000,0000,,with the general purpose of making simple things simple.
Dialogue: 0,0:40:49.40,0:40:56.21,Default,,0000,0000,0000,,so here, I want to find all v(s) in C .
Dialogue: 0,0:40:56.91,0:41:02.34,Default,,0000,0000,0000,,and C is suppose to be a container. v suppose to be a value that might be in the container.
Dialogue: 0,0:41:02.56,0:41:04.42,Default,,0000,0000,0000,,how do I want to  return that?
Dialogue: 0,0:41:04.42,0:41:09.81,Default,,0000,0000,0000,,I want to return that in vector of pointers to the elements in there.
Dialogue: 0,0:41:10.12,0:41:11.54,Default,,0000,0000,0000,,I know that the pointer is.
Dialogue: 0,0:41:11.54,0:41:21.72,Default,,0000,0000,0000,,so basically I'm gathering the addressees, the pointers to all the elements that ad value v, in a container. that's fine
Dialogue: 0,0:41:22.16,0:41:23.23,Default,,0000,0000,0000,,what's what I do.
Dialogue: 0,0:41:23.23,0:41:27.19,Default,,0000,0000,0000,,then I implemented it by making a local variable
Dialogue: 0,0:41:27.70,0:41:28.60,Default,,0000,0000,0000,,and I filled it up
Dialogue: 0,0:41:28.60,0:41:31.59,Default,,0000,0000,0000,,i use the new for loop,
Dialogue: 0,0:41:31.59,0:41:45.43,Default,,0000,0000,0000,,and I said , for x(es) in C, and x is of course of the reference type of the elements in C, the compiler knows that so I don't have to tell it, that's what "auto" says
Dialogue: 0,0:41:45.63,0:41:51.21,Default,,0000,0000,0000,,and it's references, because I want to collect information of where they were.
Dialogue: 0,0:41:51.57,0:42:01.13,Default,,0000,0000,0000,,if X equals v, push its pointer to it onto "res", when we finish, we return res.
Dialogue: 0,0:42:01.34,0:42:04.27,Default,,0000,0000,0000,,so this is like the matrix example
Dialogue: 0,0:42:04.48,0:42:10.43,Default,,0000,0000,0000,,basically I just make a collection of things and I pass it by value, return it by value
Dialogue: 0,0:42:10.89,0:42:12.48,Default,,0000,0000,0000,,and vector
Dialogue: 0,0:42:12.71,0:42:14.66,Default,,0000,0000,0000,,in c++11,
Dialogue: 0,0:42:14.92,0:42:18.84,Default,,0000,0000,0000,,a vector,  it has a move constructor. so this is actually very efficient code
Dialogue: 0,0:42:19.13,0:42:22.69,Default,,0000,0000,0000,,don't try this on c++98
Dialogue: 0,0:42:22.91,0:42:24.95,Default,,0000,0000,0000,,because it will be a performance bug
Dialogue: 0,0:42:25.18,0:42:30.42,Default,,0000,0000,0000,,but all the rest here, you can write c++11 so you are saved from that problem.
Dialogue: 0,0:42:31.06,0:42:32.38,Default,,0000,0000,0000,,and we use it (NOTE: the function find_all)
Dialogue: 0,0:42:32.39,0:42:33.44,Default,,0000,0000,0000,,take a string
Dialogue: 0,0:42:33.79,0:42:37.16,Default,,0000,0000,0000,,a string is container of characters. right?
Dialogue: 0,0:42:37.44,0:42:39.77,Default,,0000,0000,0000,,and then I say ....
Dialogue: 0,0:42:39.83,0:42:42.44,Default,,0000,0000,0000,,find_all p(es) in ...
Dialogue: 0,0:42:42.50,0:42:43.03,Default,,0000,0000,0000,,sorry
Dialogue: 0,0:42:43.46,0:42:46.75,Default,,0000,0000,0000,,for all p(s) in the result of find_all
Dialogue: 0,0:42:47.01,0:42:52.47,Default,,0000,0000,0000,,so I just going over the result, which happens to be a vector of pointers
Dialogue: 0,0:42:52.73,0:42:58.45,Default,,0000,0000,0000,,and if it doesn't points to an 'a', we have something serious here
Dialogue: 0,0:42:58.45,0:43:07.56,Default,,0000,0000,0000,,because I'm saying the 'a', and so it's a bug. string related. it's a bug in string and it's a bug in find_all or something like that.
Dialogue: 0,0:43:07.56,0:43:08.94,Default,,0000,0000,0000,,this should never happen.
Dialogue: 0,0:43:09.39,0:43:09.76,Default,,0000,0000,0000,,but
Dialogue: 0,0:43:11.42,0:43:21.31,Default,,0000,0000,0000,,so, this is fairly simple and uses a fair number of new features just to wake those of you who hasn't seen this before.
Dialogue: 0,0:43:22.72,0:43:27.26,Default,,0000,0000,0000,,let me just point out, that "auto" is the oldest c++11 feature
Dialogue: 0,0:43:27.50,0:43:33.35,Default,,0000,0000,0000,,I implemented in 1983 or 1984, some where in the winter there
Dialogue: 0,0:43:33.69,0:43:36.84,Default,,0000,0000,0000,,and (I) was forced to take it out for compatibility reasons.
Dialogue: 0,0:43:36.99,0:43:40.00,Default,,0000,0000,0000,,but it is actually a notationally very nice thing
Dialogue: 0,0:43:40.00,0:43:53.30,Default,,0000,0000,0000,,I don't have to remember what the return type of find_all is. and what is the value type of the container that came in some where.\Nthe compiler knows, so I don't have to tell it.
Dialogue: 0,0:43:53.78,0:43:57.02,Default,,0000,0000,0000,,for generic code, that's really nice.
Dialogue: 0,0:43:57.27,0:43:58.67,Default,,0000,0000,0000,,ok, so basically
Dialogue: 0,0:43:58.67,0:44:03.24,Default,,0000,0000,0000,,what I've been saying here about resource management and move semantics
Dialogue: 0,0:44:03.37,0:44:22.45,Default,,0000,0000,0000,,is deep inside the standard, all the standard containers are handles, vector list forward_list  etc etc , all the standard resources like threads, locks, files and unique pointers , use this kinds of strategy .
Dialogue: 0,0:44:22.62,0:44:22.87,Default,,0000,0000,0000,,so
Dialogue: 0,0:44:22.87,0:44:29.52,Default,,0000,0000,0000,,you don't have to start  from scratch writing this kinds of stuff, it's already in the standard library.
Dialogue: 0,0:44:29.80,0:44:32.46,Default,,0000,0000,0000,,and you are probably already using it
Dialogue: 0,0:44:33.46,0:44:38.02,Default,,0000,0000,0000,,if you are sorting in a vector, you've already using  something like the move.
Dialogue: 0,0:44:39.20,0:44:40.32,Default,,0000,0000,0000,,ok
Dialogue: 0,0:44:40.69,0:44:41.81,Default,,0000,0000,0000,,now
Dialogue: 0,0:44:41.81,0:44:48.54,Default,,0000,0000,0000,,no presentation of sort of essences of c++ could failed to mentioning object oriented programming.
Dialogue: 0,0:44:48.89,0:44:49.48,Default,,0000,0000,0000,,but you know
Dialogue: 0,0:44:49.48,0:44:57.57,Default,,0000,0000,0000,,these days, I found, just about everybody knows most of what I going to say, so I'm going to keep it very brief.
Dialogue: 0,0:44:57.85,0:45:01.19,Default,,0000,0000,0000,,c++ has a protection model
Dialogue: 0,0:45:01.30,0:45:02.60,Default,,0000,0000,0000,,for this
Dialogue: 0,0:45:02.79,0:45:06.80,Default,,0000,0000,0000,,you have public, protected and private stuff.
Dialogue: 0,0:45:06.80,0:45:08.31,Default,,0000,0000,0000,,I like stuff to be private
Dialogue: 0,0:45:08.31,0:45:14.28,Default,,0000,0000,0000,,because that limits the member or piece of code , the number of programmer that can messed it up
Dialogue: 0,0:45:14.63,0:45:16.77,Default,,0000,0000,0000,,if you have to use protected
Dialogue: 0,0:45:16.94,0:45:18.68,Default,,0000,0000,0000,,there is no universal base class
Dialogue: 0,0:45:18.68,0:45:23.65,Default,,0000,0000,0000,,because I consider I universal base class an implementation oriented artifact
Dialogue: 0,0:45:24.03,0:45:27.34,Default,,0000,0000,0000,,{\b1}there simply is nothing that is common to all types{\b0}
Dialogue: 0,0:45:27.75,0:45:30.99,Default,,0000,0000,0000,,in terms of representation or interface
Dialogue: 0,0:45:31.42,0:45:36.66,Default,,0000,0000,0000,,If you say that it has to be, you are imposing time and space overhead
Dialogue: 0,0:45:36.83,0:45:41.13,Default,,0000,0000,0000,,it might be right thing for a limited domain stuff
Dialogue: 0,0:45:41.13,0:45:44.23,Default,,0000,0000,0000,,and  maybe very useful but it's not fundamental.
Dialogue: 0,0:45:46.55,0:45:50.88,Default,,0000,0000,0000,,a universal base class easily get to  become overly general
Dialogue: 0,0:45:50.88,0:46:00.26,Default,,0000,0000,0000,,because that is really where you put many things that are common for everything, and  so you get more and more, and get hard and harder to maintain.
Dialogue: 0,0:46:00.52,0:46:02.12,Default,,0000,0000,0000,,there is multiple inheritance
Dialogue: 0,0:46:02.12,0:46:04.66,Default,,0000,0000,0000,,this is considered  contravention places
Dialogue: 0,0:46:04.89,0:46:12.61,Default,,0000,0000,0000,,but everybody who has static type in any form, has multiple inheritance of interfaces.
Dialogue: 0,0:46:12.89,0:46:15.83,Default,,0000,0000,0000,,so I consider that non-controversial.
Dialogue: 0,0:46:16.11,0:46:16.96,Default,,0000,0000,0000,,and
Dialogue: 0,0:46:16.96,0:46:29.53,Default,,0000,0000,0000,,so abstract classes provide most stable interfaces, and the best separation between users and implementers. we need multiple inheritance for that.
Dialogue: 0,0:46:29.53,0:46:33.28,Default,,0000,0000,0000,,some times it's also useful for data.
Dialogue: 0,0:46:33.39,0:46:36.21,Default,,0000,0000,0000,,there are some minimal runtime type identification
Dialogue: 0,0:46:36.42,0:46:37.68,Default,,0000,0000,0000,,so basically,
Dialogue: 0,0:46:37.93,0:46:41.54,Default,,0000,0000,0000,,you use inheritance when the domain concepts are heritable.
Dialogue: 0,0:46:41.54,0:46:42.78,Default,,0000,0000,0000,,so basically
Dialogue: 0,0:46:43.85,0:46:55.16,Default,,0000,0000,0000,,you have to think not in terms of programming languages about whether to use inheritance, you have to think in terms of the problem you try to solve, the information you're trying to represent.
Dialogue: 0,0:46:55.47,0:46:58.23,Default,,0000,0000,0000,,if you have an general hierarchical system
Dialogue: 0,0:46:59.33,0:47:03.14,Default,,0000,0000,0000,,my usual example and the oldest one is the vehicle
Dialogue: 0,0:47:04.94,0:47:06.41,Default,,0000,0000,0000,,trunk is a kind of car
Dialogue: 0,0:47:06.41,0:47:08.38,Default,,0000,0000,0000,,and is a kind of vehicle...
Dialogue: 0,0:47:08.38,0:47:09.44,Default,,0000,0000,0000,,that kinds of stuff
Dialogue: 0,0:47:09.68,0:47:12.56,Default,,0000,0000,0000,,use it, and it's very powerful.
Dialogue: 0,0:47:12.78,0:47:15.53,Default,,0000,0000,0000,,however, it has been seriously over used.
Dialogue: 0,0:47:15.65,0:47:23.99,Default,,0000,0000,0000,,that people will think, building an deep hierarchy , equals a good programming..... no!
Dialogue: 0,0:47:22.50,0:47:22.61,Default,,0000,0000,0000,,{\fs70\c&H0000FF&\pos(496,307)}NO!
Dialogue: 0,0:47:22.61,0:47:22.73,Default,,0000,0000,0000,,{\fs70\c&H0000FF&\pos(525,298)}NO!
Dialogue: 0,0:47:22.73,0:47:22.85,Default,,0000,0000,0000,,{\fs70\c&H0000FF&\pos(562,302)}NO!
Dialogue: 0,0:47:22.85,0:47:22.97,Default,,0000,0000,0000,,{\fs70\c&H0000FF&\pos(613,298)}NO!
Dialogue: 0,0:47:22.97,0:47:23.13,Default,,0000,0000,0000,,{\fs70\c&H0000FF&\pos(670,284)}NO!
Dialogue: 0,0:47:23.13,0:47:23.28,Default,,0000,0000,0000,,{\fs70\c&H0000FF&\pos(734,285)}NO!
Dialogue: 0,0:47:23.28,0:47:23.46,Default,,0000,0000,0000,,{\fs70\c&H0000FF&\pos(784,294)}NO!
Dialogue: 0,0:47:23.46,0:47:23.59,Default,,0000,0000,0000,,{\fs70\c&H0000FF&\pos(756,236)}NO!
Dialogue: 0,0:47:23.59,0:47:23.81,Default,,0000,0000,0000,,{\fs70\c&H0000FF&\pos(741,232)}NO!
Dialogue: 0,0:47:23.81,0:47:24.07,Default,,0000,0000,0000,,{\fs70\c&H0000FF&\pos(802,257)}NO!
Dialogue: 0,0:47:24.07,0:47:24.31,Default,,0000,0000,0000,,{\fs70\c&H0000FF&\pos(830,252)}NO!
Dialogue: 0,0:47:24.31,0:47:24.44,Default,,0000,0000,0000,,{\fs70\c&H0000FF&\pos(827,265)}NO!
Dialogue: 0,0:47:24.19,0:47:31.29,Default,,0000,0000,0000,,if your domain is a deep hierarchy, representing it with inheritance is just right.
Dialogue: 0,0:47:31.56,0:47:40.92,Default,,0000,0000,0000,,if your domain is a shallow hierarchy, maybe what you need is what looks like, just an interface to implementations.
Dialogue: 0,0:47:41.16,0:47:43.87,Default,,0000,0000,0000,,and maybe there is not inheritance necessary
Dialogue: 0,0:47:43.87,0:47:47.71,Default,,0000,0000,0000,,in which case you probably don't need a virtual function you don't need any hierarchy
Dialogue: 0,0:47:49.10,0:47:53.65,Default,,0000,0000,0000,,don't over do it , think before you you make a member.
Dialogue: 0,0:47:53.78,0:47:55.64,Default,,0000,0000,0000,,so ~~
Dialogue: 0,0:47:55.64,0:47:57.55,Default,,0000,0000,0000,,lets get to generic programming.
Dialogue: 0,0:47:57.55,0:48:04.50,Default,,0000,0000,0000,,this is the area that has seen most progress evolution over the many years.
Dialogue: 0,0:48:05.23,0:48:07.38,Default,,0000,0000,0000,,and there's  something to say here.
Dialogue: 0,0:48:07.57,0:48:08.36,Default,,0000,0000,0000,,basically
Dialogue: 0,0:48:08.36,0:48:14.09,Default,,0000,0000,0000,,in 1980, I wrote the first paper on C with classes. the first paper on here
Dialogue: 0,0:48:14.42,0:48:15.31,Default,,0000,0000,0000,,and
Dialogue: 0,0:48:15.40,0:48:25.96,Default,,0000,0000,0000,,it had a vector in it, it was parametrized with element type, there are statements there, and the macro will do the job.
Dialogue: 0,0:48:26.37,0:48:29.00,Default,,0000,0000,0000,,I was wrong about that.
Dialogue: 0,0:48:28.23,0:48:30.16,Default,,0000,0000,0000,,always wrong about that.
Dialogue: 0,0:48:30.16,0:48:31.68,Default,,0000,0000,0000,,on the other hand, I had right problem
Dialogue: 0,0:48:32.01,0:48:33.82,Default,,0000,0000,0000,,I want generic programming
Dialogue: 0,0:48:34.22,0:48:43.76,Default,,0000,0000,0000,,I wanted , my vector, to be parametrized on the element type, not my sort function, to work independently which element type it was.
Dialogue: 0,0:48:44.28,0:48:48.31,Default,,0000,0000,0000,,so, in ... in 1987
Dialogue: 0,0:48:49.43,0:48:56.83,Default,,0000,0000,0000,,I wrote out the aims and design templates it has to be extremely general and flexible
Dialogue: 0,0:48:56.99,0:49:02.07,Default,,0000,0000,0000,,if it only can do what I imagine, that's something wrong
Dialogue: 0,0:49:02.07,0:49:09.82,Default,,0000,0000,0000,,because my imagination is not equal to the needs of even a room of people like this. let along all the programmers at all.
Dialogue: 0,0:49:10.29,0:49:12.01,Default,,0000,0000,0000,,there has to be zero overhead.
Dialogue: 0,0:49:12.58,0:49:17.63,Default,,0000,0000,0000,,the reason was, that my least favorite data type in c and c++ is the array.
Dialogue: 0,0:49:18.51,0:49:25.16,Default,,0000,0000,0000,,and the array in C , is a data type that so stupid it doesn't even know how many elements it got.
Dialogue: 0,0:49:25.62,0:49:33.85,Default,,0000,0000,0000,,that's a source for a lot of problems. it also converts in strange ways, it .. it .. it's problematic.
Dialogue: 0,0:49:33.85,0:49:43.15,Default,,0000,0000,0000,,so i would like to have a vector or matrix that would be a useful replacement for arrays in most cases.
Dialogue: 0,0:49:43.50,0:49:54.50,Default,,0000,0000,0000,,and , the C part of the c++ community are upset to the performance, so basic the "zero overhead"  comes in here, not a byte , not a cycle
Dialogue: 0,0:49:54.68,0:49:55.20,Default,,0000,0000,0000,,so
Dialogue: 0,0:49:55.20,0:49:56.84,Default,,0000,0000,0000,,we have to be able to do that.
Dialogue: 0,0:49:57.22,0:50:00.56,Default,,0000,0000,0000,,you have to remember that most people will think about abstraction
Dialogue: 0,0:50:00.68,0:50:01.71,Default,,0000,0000,0000,,and generic code
Dialogue: 0,0:50:01.71,0:50:03.61,Default,,0000,0000,0000,,thinks about indirect function calls.
Dialogue: 0,0:50:04.12,0:50:12.27,Default,,0000,0000,0000,,you can't go through a jump table and still have performance comparable with manipulating arrays.
Dialogue: 0,0:50:12.62,0:50:23.12,Default,,0000,0000,0000,,imagination if you are operation for subscripting or you are operation for going two elements over in an arrays, was a virtual function call.
Dialogue: 0,0:50:23.28,0:50:29.29,Default,,0000,0000,0000,,you're dead in the world that compare to arrays, and the arrays will live forever.
Dialogue: 0,0:50:29.29,0:50:30.10,Default,,0000,0000,0000,,so
Dialogue: 0,0:50:30.10,0:50:39.64,Default,,0000,0000,0000,,and also of course I want well specified interfaces like everybody else.{\n}I knew that well specified interface is the foundation for a lot of good architecture stuff.
Dialogue: 0,0:50:40.02,0:50:47.56,Default,,0000,0000,0000,,I was the one who put function argument checking and conversion into c++
Dialogue: 0,0:50:47.82,0:50:51.00,Default,,0000,0000,0000,,what later and  C because function prototypes and such.
Dialogue: 0,0:50:51.00,0:50:54.66,Default,,0000,0000,0000,,it's one of the first things I did. I knew the value of that.
Dialogue: 0,0:50:55.02,0:50:58.23,Default,,0000,0000,0000,,on the other hand you know, I didn't make it.
Dialogue: 0,0:50:58.67,0:51:00.48,Default,,0000,0000,0000,,two out of three ain't bad.
Dialogue: 0,0:51:00.48,0:51:02.18,Default,,0000,0000,0000,,got the first two.
Dialogue: 0,0:51:02.18,0:51:04.42,Default,,0000,0000,0000,,but the third , failed miserably.
Dialogue: 0,0:51:04.42,0:51:11.06,Default,,0000,0000,0000,,it has kept me concerned/worried  and working on it for 20 years.
Dialogue: 0,0:51:11.06,0:51:14.54,Default,,0000,0000,0000,,I'm going to finish this talk, showing where the current state of that work is
Dialogue: 0,0:51:14.96,0:51:15.92,Default,,0000,0000,0000,,but basically
Dialogue: 0,0:51:15.92,0:51:18.19,Default,,0000,0000,0000,,I don't think I had a choice back in 1983.
Dialogue: 0,0:51:18.19,0:51:21.87,Default,,0000,0000,0000,,I don't think anybody knew how to get 3 simultaneously.
Dialogue: 0,0:51:22.07,0:51:24.60,Default,,0000,0000,0000,,and if you have to pick only two ...
Dialogue: 0,0:51:24.60,0:51:25.53,Default,,0000,0000,0000,,well
Dialogue: 0,0:51:25.53,0:51:26.54,Default,,0000,0000,0000,,I made my choice.
Dialogue: 0,0:51:26.54,0:51:28.71,Default,,0000,0000,0000,,therefore for c++, probably might be the right thing
Dialogue: 0,0:51:29.34,0:51:29.70,Default,,0000,0000,0000,,so
Dialogue: 0,0:51:29.70,0:51:30.95,Default,,0000,0000,0000,,what we have from templates?
Dialogue: 0,0:51:30.95,0:51:33.46,Default,,0000,0000,0000,,they do compile time duck typing
Dialogue: 0,0:51:33.46,0:51:38.21,Default,,0000,0000,0000,,basically, they expand the code, and they check the expanded code.
Dialogue: 0,0:51:38.77,0:51:41.61,Default,,0000,0000,0000,,and that leads to template meta programming.
Dialogue: 0,0:51:41.61,0:51:47.05,Default,,0000,0000,0000,,it leads to very good weaving of information from different sources.
Dialogue: 0,0:51:47.05,0:51:53.68,Default,,0000,0000,0000,,but it also means, that an  error is found in the generated code, in the instantiated code
Dialogue: 0,0:51:53.96,0:51:58.30,Default,,0000,0000,0000,,and most of you while you seen these error messages, you can get out of that.
Dialogue: 0,0:51:59.02,0:52:06.29,Default,,0000,0000,0000,,I used to think of that, sooner or later, the compiler writers will get smart enough to write decent error messages
Dialogue: 0,0:52:06.62,0:52:08.97,Default,,0000,0000,0000,,but ... I was ...
Dialogue: 0,0:52:09.89,0:52:11.29,Default,,0000,0000,0000,,well, it hasn't happened.
Dialogue: 0,0:52:11.29,0:52:17.55,Default,,0000,0000,0000,,I still get error messages that doesn't fit on my linux window
Dialogue: 0,0:52:17.89,0:52:21.63,Default,,0000,0000,0000,,they scroll off the top of the window and I never see the top one
Dialogue: 0,0:52:21.63,0:52:22.37,Default,,0000,0000,0000,,things like that.
Dialogue: 0,0:52:22.63,0:52:24.43,Default,,0000,0000,0000,,ok, we need to do something about that.
Dialogue: 0,0:52:24.78,0:52:25.72,Default,,0000,0000,0000,,but, let's see.
Dialogue: 0,0:52:26.54,0:52:33.75,Default,,0000,0000,0000,,template is a massive success in (c++)98, it was better on later c++11, and it will be better in c++14.
Dialogue: 0,0:52:34.01,0:52:34.89,Default,,0000,0000,0000,,basically
Dialogue: 0,0:52:34.89,0:52:37.11,Default,,0000,0000,0000,,we have containers, we have algorithms
Dialogue: 0,0:52:37.11,0:52:40.72,Default,,0000,0000,0000,,they are in standard library organized as STL
Dialogue: 0,0:52:41.14,0:52:42.02,Default,,0000,0000,0000,,err.
Dialogue: 0,0:52:42.46,0:52:44.53,Default,,0000,0000,0000,,which stands for STL(NOTE, Bjarne would have said Standard Template Library).
Dialogue: 0,0:52:44.88,0:52:47.02,Default,,0000,0000,0000,,and ...
Dialogue: 0,0:52:47.02,0:52:48.85,Default,,0000,0000,0000,,there is(will be) much more.
Dialogue: 0,0:52:48.85,0:52:51.83,Default,,0000,0000,0000,,I need better support for compile time programming
Dialogue: 0,0:52:51.83,0:52:55.58,Default,,0000,0000,0000,,because template meta programming gets too complicated often
Dialogue: 0,0:52:55.83,0:52:59.80,Default,,0000,0000,0000,,constexpr provides a facility in c++11
Dialogue: 0,0:52:59.81,0:53:01.62,Default,,0000,0000,0000,,it's  generalized const expression
Dialogue: 0,0:53:01.62,0:53:02.25,Default,,0000,0000,0000,,basically
Dialogue: 0,0:53:02.25,0:53:08.18,Default,,0000,0000,0000,,you can define functions that are to be evaluated at compile time.
Dialogue: 0,0:53:08.18,0:53:13.31,Default,,0000,0000,0000,,you can force compile time evaluation in-places
Dialogue: 0,0:53:13.72,0:53:15.37,Default,,0000,0000,0000,,and
Dialogue: 0,0:53:16.11,0:53:22.58,Default,,0000,0000,0000,,you can do const expression evaluation at compile time for user defined types.
Dialogue: 0,0:53:22.93,0:53:26.39,Default,,0000,0000,0000,,provided that user defined types are simple enough know as literal types.
Dialogue: 0,0:53:26.61,0:53:30.34,Default,,0000,0000,0000,,I know some of the talks there will get into some of that.
Dialogue: 0,0:53:30.86,0:53:32.78,Default,,0000,0000,0000,,OK, we are making progress.
Dialogue: 0,0:53:33.08,0:53:34.27,Default,,0000,0000,0000,,basically
Dialogue: 0,0:53:34.27,0:53:38.22,Default,,0000,0000,0000,,what we have now, and what we looking for, is algorithms
Dialogue: 0,0:53:38.39,0:53:46.13,Default,,0000,0000,0000,,we must get away from writing all our code from scratch in the basic language
Dialogue: 0,0:53:46.40,0:54:00.26,Default,,0000,0000,0000,,we need to raise our level of abstraction to the point where instead of everybody everything been  just integer adds and subtracts ,and things  like that. we say, we use these algorithms like out of catalog algorithms.
Dialogue: 0,0:54:00.52,0:54:02.58,Default,,0000,0000,0000,,and here's sort of classic examples
Dialogue: 0,0:54:02.58,0:54:06.62,Default,,0000,0000,0000,,we sort a vector, and we find an element in a vector.
Dialogue: 0,0:54:07.09,0:54:12.54,Default,,0000,0000,0000,,the STL works on sequences of things, so we have to have the beginning and the end.
Dialogue: 0,0:54:12.79,0:54:13.90,Default,,0000,0000,0000,,but basically
Dialogue: 0,0:54:13.90,0:54:19.20,Default,,0000,0000,0000,,this is parametrized, it is generic or the kind of container we are dealing with
Dialogue: 0,0:54:19.20,0:54:20.46,Default,,0000,0000,0000,,here is a vector, here is a list
Dialogue: 0,0:54:20.46,0:54:21.92,Default,,0000,0000,0000,,and it's goo....
Dialogue: 0,0:54:21.92,0:54:25.52,Default,,0000,0000,0000,,it's generic over the elements of those containers.
Dialogue: 0,0:54:25.52,0:54:26.98,Default,,0000,0000,0000,,there is ....
Dialogue: 0,0:54:27.75,0:54:28.74,Default,,0000,0000,0000,,let me think about
Dialogue: 0,0:54:28.74,0:54:31.52,Default,,0000,0000,0000,,a hundred algorithms now that's standard
Dialogue: 0,0:54:31.52,0:54:36.24,Default,,0000,0000,0000,,and I 'll hope you'll writing your own and add to it(the standard)
Dialogue: 0,0:54:36.24,0:54:38.24,Default,,0000,0000,0000,,we don't see too much of that as we should.
Dialogue: 0,0:54:38.24,0:54:40.24,Default,,0000,0000,0000,,basically
Dialogue: 0,0:54:40.24,0:54:44.90,Default,,0000,0000,0000,,we want simple and efficient and general implementations.
Dialogue: 0,0:54:45.19,0:54:45.53,Default,,0000,0000,0000,,here
Dialogue: 0,0:54:45.53,0:54:52.21,Default,,0000,0000,0000,,here  we got find, if you like C syntax, it is beautiful, if you don't , that's what you've got anyway.
Dialogue: 0,0:54:53.51,0:54:57.26,Default,,0000,0000,0000,,and also we want to parametrized with operations
Dialogue: 0,0:54:57.26,0:54:57.90,Default,,0000,0000,0000,,that is
Dialogue: 0,0:54:57.90,0:55:06.01,Default,,0000,0000,0000,,we parametrized over the container.  we parametrized over the element type, and we parametrized over the actions to be taken
Dialogue: 0,0:55:06.01,0:55:12.14,Default,,0000,0000,0000,,here is the predicate passed to find_if, I want to find anything that meets predicate less_than\{"Griffin"\}
Dialogue: 0,0:55:13.55,0:55:14.63,Default,,0000,0000,0000,,and
Dialogue: 0,0:55:15.07,0:55:21.20,Default,,0000,0000,0000,,so we generalized find_if that was shown before, if simply uses the predicate
Dialogue: 0,0:55:21.20,0:55:27.56,Default,,0000,0000,0000,,while we haven't reaches the end , we didn't find predicate and then goes to next one and try again.
Dialogue: 0,0:55:27.56,0:55:31.54,Default,,0000,0000,0000,,if the point you finish, you return.
Dialogue: 0,0:55:31.54,0:55:41.11,Default,,0000,0000,0000,,ok, there is spin in c++ in various ways since late 80s, early 90s.
Dialogue: 0,0:55:41.11,0:55:50.66,Default,,0000,0000,0000,,so we write a lot of function objects, that's the way we represent operations, predicates, etc.
Dialogue: 0,0:55:50.66,0:55:52.87,Default,,0000,0000,0000,,{\b1}they can carry {\b1\3c&H0000FF&}states{\b0\3c0&0}, that's important.{\b0}
Dialogue: 0,0:55:53.01,0:55:59.77,Default,,0000,0000,0000,,there are easily inlineed , they actually work better in simple cases than an indirect function call.
Dialogue: 0,0:56:00.05,0:56:01.05,Default,,0000,0000,0000,,and so here
Dialogue: 0,0:56:01.23,0:56:07.12,Default,,0000,0000,0000,,less_than(strings) that suppose to take a string you'll compare it to , and then compare when you ask it.
Dialogue: 0,0:56:07.39,0:56:10.34,Default,,0000,0000,0000,,and that's how it was done.
Dialogue: 0,0:56:10.61,0:56:12.10,Default,,0000,0000,0000,,here
Dialogue: 0,0:56:12.10,0:56:18.31,Default,,0000,0000,0000,,take the "Griffin" that's what I want to compare to, and whenever I want to compare, it calls the object.
Dialogue: 0,0:56:18.59,0:56:23.04,Default,,0000,0000,0000,,if you get tired to write these function objects, we can use lambda instead.
Dialogue: 0,0:56:23.30,0:56:28.62,Default,,0000,0000,0000,,which is basically a notation that says, give me a function object and use it right here.
Dialogue: 0,0:56:28.97,0:56:29.76,Default,,0000,0000,0000,,so here
Dialogue: 0,0:56:29.76,0:56:38.67,Default,,0000,0000,0000,,I want to , to , to do the  find_all, and I want to compare to the value "Griffin"
Dialogue: 0,0:56:38.95,0:56:39.46,Default,,0000,0000,0000,,done.
Dialogue: 0,0:56:40.07,0:56:45.00,Default,,0000,0000,0000,,if you get tired of writing all these begins, you don't have to
Dialogue: 0,0:56:45.23,0:56:49.64,Default,,0000,0000,0000,,you can simply define your own versions that works over a container.
Dialogue: 0,0:56:49.82,0:56:58.41,Default,,0000,0000,0000,,it's not perfectly as general as using pairs of iterators, it is notationally much nicer.
Dialogue: 0,0:56:58.43,0:57:00.16,Default,,0000,0000,0000,,so here is the find_if()
Dialogue: 0,0:57:00.16,0:57:07.17,Default,,0000,0000,0000,,find_if in the container c, that look for things that are odd
Dialogue: 0,0:57:08.55,0:57:10.61,Default,,0000,0000,0000,,ok
Dialogue: 0,0:57:10.73,0:57:11.36,Default,,0000,0000,0000,,err
Dialogue: 0,0:57:11.36,0:57:14.66,Default,,0000,0000,0000,,back to the problem of specifying interfaces.
Dialogue: 0,0:57:14.66,0:57:24.23,Default,,0000,0000,0000,,I find that duck typing is in-sufficient,it gives all of those bad error messages in addiction to what ever the good it does.
Dialogue: 0,0:57:24.23,0:57:27.41,Default,,0000,0000,0000,,it leaves error detection too late
Dialogue: 0,0:57:27.41,0:57:29.99,Default,,0000,0000,0000,,and it gives compiler writers  too hard job
Dialogue: 0,0:57:29.99,0:57:32.18,Default,,0000,0000,0000,,because there are no proper interfaces
Dialogue: 0,0:57:32.43,0:57:36.90,Default,,0000,0000,0000,,these is no way else says, this is what the algorithms requires over its' arguments.
Dialogue: 0,0:57:37.35,0:57:42.33,Default,,0000,0000,0000,,this is not sit some where , there is no way for us to say it in c++11.
Dialogue: 0,0:57:44.97,0:57:51.30,Default,,0000,0000,0000,,that also encourage people to look at the implementation details, because they will look at them anyway.
Dialogue: 0,0:57:52.08,0:57:56.64,Default,,0000,0000,0000,,there is no interface that protected them from the details.
Dialogue: 0,0:57:56.64,0:57:58.14,Default,,0000,0000,0000,,and that means that ...
Dialogue: 0,0:57:58.14,0:58:11.56,Default,,0000,0000,0000,,every time you change the implementation of an algorithm, some user might be affected in an surprising way, so that users interest what's inside those abstractions. they are no data abstract.
Dialogue: 0,0:58:12.19,0:58:17.19,Default,,0000,0000,0000,,that leads to people start generalize their implementations so that ...
Dialogue: 0,0:58:17.67,0:58:19.12,Default,,0000,0000,0000,,users
Dialogue: 0,0:58:19.12,0:58:20.60,Default,,0000,0000,0000,,so that they have a great user base.
Dialogue: 0,0:58:20.76,0:58:23.61,Default,,0000,0000,0000,,this gets to a mass some times.
Dialogue: 0,0:58:23.96,0:58:27.99,Default,,0000,0000,0000,,and further more it doesn't integrate too well with other parts of the language.
Dialogue: 0,0:58:27.99,0:58:34.44,Default,,0000,0000,0000,,you have to teach this kinds of coding in a different way than other kinds of coding.
Dialogue: 0,0:58:34.65,0:58:38.71,Default,,0000,0000,0000,,and you have to to to to think about in a different way.
Dialogue: 0,0:58:38.71,0:58:39.54,Default,,0000,0000,0000,,that's not good.
Dialogue: 0,0:58:39.54,0:58:45.13,Default,,0000,0000,0000,,we are not good at keeping one style here, and one style there. it should be better integrated.
Dialogue: 0,0:58:45.13,0:58:51.75,Default,,0000,0000,0000,,so, I think we have to rethink generic code, so that it become similar to the way we think about other code.
Dialogue: 0,0:58:51.75,0:58:57.36,Default,,0000,0000,0000,,and we need interfaces to get better error messages,  better specification of our algorithms.
Dialogue: 0,0:58:57.36,0:58:58.22,Default,,0000,0000,0000,,so
Dialogue: 0,0:58:58.36,0:59:00.31,Default,,0000,0000,0000,,here is what I like.
Dialogue: 0,0:59:00.37,0:59:01.84,Default,,0000,0000,0000,,here is some traditional code
Dialogue: 0,0:59:01.93,0:59:03.79,Default,,0000,0000,0000,,we have a square root of double
Dialogue: 0,0:59:03.79,0:59:05.12,Default,,0000,0000,0000,,we return to double
Dialogue: 0,0:59:05.21,0:59:06.05,Default,,0000,0000,0000,,we have a double
Dialogue: 0,0:59:06.05,0:59:08.16,Default,,0000,0000,0000,,we call the square root of double with the double
Dialogue: 0,0:59:08.16,0:59:09.80,Default,,0000,0000,0000,,every thing is fine
Dialogue: 0,0:59:09.80,0:59:15.18,Default,,0000,0000,0000,,that's what we learned in some versions of our long day one of programming class.
Dialogue: 0,0:59:15.18,0:59:18.09,Default,,0000,0000,0000,,and if we give something to square root that isn't a double
Dialogue: 0,0:59:18.39,0:59:20.83,Default,,0000,0000,0000,,in this case, a pointer to double
Dialogue: 0,0:59:20.83,0:59:26.89,Default,,0000,0000,0000,,we get an error{\k0} at compile time right there, simple, straight forward.  we all understood that. very simple.
Dialogue: 0,0:59:26.89,0:59:30.09,Default,,0000,0000,0000,,now I want to see the same thing with generic code
Dialogue: 0,0:59:30.09,0:59:32.57,Default,,0000,0000,0000,,here is a sort, that sorts containers.
Dialogue: 0,0:59:33.06,0:59:34.23,Default,,0000,0000,0000,,here's a container.
Dialogue: 0,0:59:34.80,0:59:35.99,Default,,0000,0000,0000,,fine
Dialogue: 0,0:59:38.64,0:59:40.13,Default,,0000,0000,0000,,we sort the container.
Dialogue: 0,0:59:40.24,0:59:40.59,Default,,0000,0000,0000,,here
Dialogue: 0,0:59:40.59,0:59:43.03,Default,,0000,0000,0000,,when it's time to sort something that's not a container.
Dialogue: 0,0:59:43.13,0:59:45.56,Default,,0000,0000,0000,,in this case is a pointer of a container.
Dialogue: 0,0:59:45.92,0:59:47.35,Default,,0000,0000,0000,,and we should get an error
Dialogue: 0,0:59:47.35,0:59:51.14,Default,,0000,0000,0000,,we should get an error right here, and it should be comprehensive.
Dialogue: 0,0:59:51.14,0:59:57.41,Default,,0000,0000,0000,,so I would like to see a generic programming that's very similar to ordinary programming.
Dialogue: 0,0:59:58.20,0:59:59.15,Default,,0000,0000,0000,,so
Dialogue: 0,0:59:59.43,1:00:03.11,Default,,0000,0000,0000,,this is what we have working with, something called concepts lite.
Dialogue: 0,1:00:03.11,1:00:04.75,Default,,0000,0000,0000,,it is also known as constraints
Dialogue: 0,1:00:04.75,1:00:13.21,Default,,0000,0000,0000,,but after people have talking about concepts for a decade, in variably they became concepts.
Dialogue: 0,1:00:13.21,1:00:22.56,Default,,0000,0000,0000,,but since they bundle less than 1/10 of the complexity of the old c++0x concepts, it became concept lite.
Dialogue: 0,1:00:22.98,1:00:25.79,Default,,0000,0000,0000,,sorry to Coca-Cola what ever.
Dialogue: 0,1:00:26.40,1:00:27.87,Default,,0000,0000,0000,,err, so , basically
Dialogue: 0,1:00:27.87,1:00:38.18,Default,,0000,0000,0000,,we are trying to answer the question how doe we specify requirements on template argument, we want to state the intent and we want point-of-use checking.
Dialogue: 0,1:00:38.27,1:00:38.58,Default,,0000,0000,0000,,so
Dialogue: 0,1:00:38.58,1:00:46.40,Default,,0000,0000,0000,,we are basically providing set of functions that states what we are requiring of an algorithm.
Dialogue: 0,1:00:46.63,1:00:47.36,Default,,0000,0000,0000,,so
Dialogue: 0,1:00:47.97,1:00:51.97,Default,,0000,0000,0000,,if i have an algorithm for sorts, it will ask for an container
Dialogue: 0,1:00:52.85,1:01:02.67,Default,,0000,0000,0000,,if i had an algorithm that take square root, it ask for a double of positive number
Dialogue: 0,1:01:03.58,1:01:04.24,Default,,0000,0000,0000,,and
Dialogue: 0,1:01:05.65,1:01:09.11,Default,,0000,0000,0000,,this is voted as c++14 technical report
Dialogue: 0,1:01:09.11,1:01:12.15,Default,,0000,0000,0000,,technical specification, I believe it's the technical term.
Dialogue: 0,1:01:12.40,1:01:16.49,Default,,0000,0000,0000,,It designed by me, Gonçalo dos Reis and Andrew Sutton.
Dialogue: 0,1:01:16.49,1:01:21.51,Default,,0000,0000,0000,,Andrew Sutton has the basic implementation of all the basic stuff and most of the details
Dialogue: 0,1:01:21.90,1:01:22.43,Default,,0000,0000,0000,,and
Dialogue: 0,1:01:22.46,1:01:30.72,Default,,0000,0000,0000,,basically for those of you who have lift through the c++0x concepts,
Dialogue: 0,1:01:30.72,1:01:37.46,Default,,0000,0000,0000,,there are not concept maps, there are no new syntax, and there are no scope and look up issues.
Dialogue: 0,1:01:37.46,1:01:40.23,Default,,0000,0000,0000,,the specification is very much simpler.
Dialogue: 0,1:01:40.23,1:01:45.05,Default,,0000,0000,0000,,so, the first thing we have to ask ourself when working on those,
Dialogue: 0,1:01:45.06,1:01:45.96,Default,,0000,0000,0000,,what are concepts?
Dialogue: 0,1:01:46.03,1:01:50.25,Default,,0000,0000,0000,,and one of the notions that we came up with what is concepts are fundamental.
Dialogue: 0,1:01:51.16,1:01:57.38,Default,,0000,0000,0000,,people were writing specifications that were very very detail in theory.
Dialogue: 0,1:01:58.40,1:02:03.29,Default,,0000,0000,0000,,there literally  was 120 concepts in c++ standard library.
Dialogue: 0,1:02:03.56,1:02:15.23,Default,,0000,0000,0000,,and look at it, how many concepts are there in the algebra ? a dozen ? is c++ standard library 10 times  complicated as algebra?
Dialogue: 0,1:02:15.44,1:02:19.76,Default,,0000,0000,0000,,I hope not. it certainly does not have 10 time as many fundamental concepts.
Dialogue: 0,1:02:19.80,1:02:30.56,Default,,0000,0000,0000,,so we have to concentrate on building concepts in a language as what you have that a fundamental application area.
Dialogue: 0,1:02:30.60,1:02:38.06,Default,,0000,0000,0000,,you has to remember that concept comes to classes that describes that area, you don't have a free choice really.
Dialogue: 0,1:02:38.57,1:02:41.06,Default,,0000,0000,0000,,if you are dealing with arithmetic
Dialogue: 0,1:02:41.12,1:02:49.61,Default,,0000,0000,0000,,you can't define what it means to subtract independently what it means to define addition.
Dialogue: 0,1:02:49.81,1:02:57.20,Default,,0000,0000,0000,,you can not define multiplication independently of the first two. these things hang together.
Dialogue: 0,1:02:57.20,1:03:03.31,Default,,0000,0000,0000,,it is not just syntax, subtractable is not a concept, it's something you can say,
Dialogue: 0,1:03:03.32,1:03:10.69,Default,,0000,0000,0000,,but it doesn't make any sense except in the context of something that's specified , say arithmetic.
Dialogue: 0,1:03:10.69,1:03:18.43,Default,,0000,0000,0000,,and we always have concepts. notice that, C have concepts. integer, arithmetic ,
Dialogue: 0,1:03:19.33,1:03:29.64,Default,,0000,0000,0000,,they are just words in the standard, just like c++ forward iterator, and predicate.
Dialogue: 0,1:03:29.83,1:03:31.33,Default,,0000,0000,0000,,are just words
Dialogue: 0,1:03:31.49,1:03:35.89,Default,,0000,0000,0000,,in the standard. we want to make it real into code.
Dialogue: 0,1:03:36.29,1:03:42.68,Default,,0000,0000,0000,,so, basically we are looking for some thing fundamental. don't expect to find something fundamental every year.
Dialogue: 0,1:03:42.69,1:03:51.59,Default,,0000,0000,0000,,I don't expect to once we got a body of concept to describe things, I don't expect to fond one every year.
Dialogue: 0,1:03:51.59,1:03:54.96,Default,,0000,0000,0000,,it is not the minimal requirements for an implementation.
Dialogue: 0,1:03:54.96,1:04:02.61,Default,,0000,0000,0000,,if every algorithm is specified as minimal requirement for it's implementation.we have a problem.
Dialogue: 0,1:04:02.61,1:04:08.11,Default,,0000,0000,0000,,if we want to improve the implementation we have to change the interface.that's bridle.
Dialogue: 0,1:04:08.36,1:04:14.82,Default,,0000,0000,0000,,what we need to do, is specify interfaces in terms of general concepts
Dialogue: 0,1:04:14.85,1:04:19.39,Default,,0000,0000,0000,,so that we can improve the implementations without affecting the users
Dialogue: 0,1:04:19.39,1:04:25.56,Default,,0000,0000,0000,,we also want to have so few concepts that we actually have a chance of remembering them.
Dialogue: 0,1:04:25.56,1:04:32.60,Default,,0000,0000,0000,,I couldn't remember that sole of concepts in c++0x
Dialogue: 0,1:04:33.30,1:04:42.04,Default,,0000,0000,0000,,I do expect to be able to remember the concepts in c++14, or 17, what ever. because there will be few hands of them.
Dialogue: 0,1:04:42.10,1:04:49.35,Default,,0000,0000,0000,,Andrew Sutton and me , work on something and we got the STL down to 16 concepts.
Dialogue: 0,1:04:49.57,1:04:54.56,Default,,0000,0000,0000,,I believe current version is that thing.
Dialogue: 0,1:04:55.62,1:04:58.44,Default,,0000,0000,0000,,A concept is a predicate on one or more arguments.
Dialogue: 0,1:05:00.06,1:05:02.47,Default,,0000,0000,0000,,we say that T suppose to be a sequence
Dialogue: 0,1:05:03.28,1:05:07.04,Default,,0000,0000,0000,,simply at compile time, we check whether T is a sequence
Dialogue: 0,1:05:07.11,1:05:15.27,Default,,0000,0000,0000,,some where, there's definition of what is it that meets sequence, has an begin an end , for instance, and we just ask if T meets that
Dialogue: 0,1:05:15.94,1:05:20.59,Default,,0000,0000,0000,,if it's a sequence, answer is true, if it's not, answer is false.
Dialogue: 0,1:05:20.78,1:05:22.19,Default,,0000,0000,0000,,we can do that on compile time.
Dialogue: 0,1:05:22.27,1:05:30.29,Default,,0000,0000,0000,,we have constexpr functions we have functions that can be evaluated at compile time. and we can write things like that.
Dialogue: 0,1:05:30.52,1:05:33.13,Default,,0000,0000,0000,,this is by the way , describe running code
Dialogue: 0,1:05:33.22,1:05:39.72,Default,,0000,0000,0000,,you can download a branch of gcc and try it today.\Nthis is not science fiction.
Dialogue: 0,1:05:40.00,1:05:46.25,Default,,0000,0000,0000,,template declaration will look bit like, you can write like this
Dialogue: 0,1:05:46.25,1:06:04.38,Default,,0000,0000,0000,,here we have find, basically we have need a sequence S, and we need something for the value type of sequence S can compare equal to that of value type T. and so it takes a sequence and a value of that type.
Dialogue: 0,1:06:04.59,1:06:07.28,Default,,0000,0000,0000,,and now we can write code like that.
Dialogue: 0,1:06:07.43,1:06:10.07,Default,,0000,0000,0000,,it looks exactly as it used to.
Dialogue: 0,1:06:10.21,1:06:20.82,Default,,0000,0000,0000,,the only difference is, we specified find , precisely , so that all the information for checking is available at the point here.
Dialogue: 0,1:06:20.82,1:06:22.16,Default,,0000,0000,0000,,so lets see what happens.
Dialogue: 0,1:06:22.41,1:06:28.04,Default,,0000,0000,0000,,here, we have sortable concept some where, and it takes a container.
Dialogue: 0,1:06:28.26,1:06:32.14,Default,,0000,0000,0000,,we take one container which is a vector, one container which is a list.
Dialogue: 0,1:06:32.40,1:06:34.34,Default,,0000,0000,0000,,and we sort the vector.
Dialogue: 0,1:06:34.55,1:06:36.59,Default,,0000,0000,0000,,ok, the vector is sortable
Dialogue: 0,1:06:37.47,1:06:46.03,Default,,0000,0000,0000,,sortable ask for things like random iterator, which means you can do subscripting like that, every thing is fine.
Dialogue: 0,1:06:46.14,1:06:50.65,Default,,0000,0000,0000,,sort a list, will fail --  because list is not actually sortable.
Dialogue: 0,1:06:50.82,1:06:56.04,Default,,0000,0000,0000,,they don't have the necessary stuff to poke in different parts of an object.
Dialogue: 0,1:06:56.38,1:07:01.58,Default,,0000,0000,0000,,the best way to sort list is tern to be copy it to a vector, sort and copy it back again.
Dialogue: 0,1:07:01.65,1:07:03.39,Default,,0000,0000,0000,,but that's beyond the ....
Dialogue: 0,1:07:03.52,1:07:04.52,Default,,0000,0000,0000,,it not on here. (BS 说不关他的事)
Dialogue: 0,1:07:04.52,1:07:06.10,Default,,0000,0000,0000,,instead, it gives us an error .
Dialogue: 0,1:07:06.32,1:07:10.13,Default,,0000,0000,0000,,so here is actual error message from this code.
Dialogue: 0,1:07:10.92,1:07:14.51,Default,,0000,0000,0000,,list<int> does not satisfy the constraint 'sortable'.
Dialogue: 0,1:07:15.01,1:07:17.47,Default,,0000,0000,0000,,and if you hit, oh
Dialogue: 0,1:07:17.47,1:07:18.35,Default,,0000,0000,0000,,Thank You.
Dialogue: 0,1:07:18.35,1:07:27.45,Default,,0000,0000,0000,,。。。
Dialogue: 0,1:07:27.62,1:07:33.39,Default,,0000,0000,0000,,by the way, if you hit another compile option, it will tell you why list is not sortable.
Dialogue: 0,1:07:33.60,1:07:40.71,Default,,0000,0000,0000,,it will come back and tell you .... that it couldn't  ... it it it doesn't know where the scrap ???
Dialogue: 0,1:07:42.19,1:07:43.00,Default,,0000,0000,0000,,but that's
Dialogue: 0,1:07:43.00,1:07:43.48,Default,,0000,0000,0000,,.. that's ...
Dialogue: 0,1:07:43.48,1:07:44.60,Default,,0000,0000,0000,,...em...
Dialogue: 0,1:07:44.69,1:07:48.30,Default,,0000,0000,0000,,I like the short version and who likes the longer version.
Dialogue: 0,1:07:48.97,1:07:50.13,Default,,0000,0000,0000,,so that's switchable
Dialogue: 0,1:07:50.13,1:07:57.86,Default,,0000,0000,0000,,the shorthand notation is if you don't want to write all of these require stuff, you come upset
Dialogue: 0,1:07:57.86,1:08:10.82,Default,,0000,0000,0000,,you can actually write: we need a sequence S, for which the value type of the sequence is equality comparable to the other template argument T.
Dialogue: 0,1:08:11.35,1:08:15.36,Default,,0000,0000,0000,,and we can say  iterator T find  ... well.
Dialogue: 0,1:08:15.36,1:08:18.56,Default,,0000,0000,0000,,some people like this notations some people like the others.
Dialogue: 0,1:08:18.70,1:08:20.50,Default,,0000,0000,0000,,you have a choice. (和前面说 template syntax 没有选择呼应了。)
Dialogue: 0,1:08:20.50,1:08:25.10,Default,,0000,0000,0000,,this is just the shorthand. it expand to the "requires" version.
Dialogue: 0,1:08:25.29,1:08:29.23,Default,,0000,0000,0000,,and we can handle essentially all of the Palo Alto technical report.
Dialogue: 0,1:08:29.23,1:08:39.82,Default,,0000,0000,0000,,Palo Alto technical report is a hundred sum page of document specify every algorithm in the STL
Dialogue: 0,1:08:39.82,1:08:46.14,Default,,0000,0000,0000,,and this was done by a group of about twenty people in Palo Alto two years ago.
Dialogue: 0,1:08:47.46,1:08:51.83,Default,,0000,0000,0000,,Jon (Jon Kalb) was there, I was there ... about twenty (people)
Dialogue: 0,1:08:51.83,1:09:01.69,Default,,0000,0000,0000,,it was called by Andrew Lumsdaine from Indiana (University ), which is one of the main workerson the c++0x concept.
Dialogue: 0,1:09:01.69,1:09:11.56,Default,,0000,0000,0000,,and got Alex Stepanov, who is the father of STL , to chair it, and we spend a week, simple specify everything.
Dialogue: 0,1:09:12.34,1:09:23.14,Default,,0000,0000,0000,,so, first, you figure out what you want, and then you figure out how design a language which will do it. that's the right way around.Don't go and look for fancy language features and see how can can use them.
Dialogue: 0,1:09:17.66,1:09:19.38,Default,,0000,0000,0000,,{\pos(712,163)\c&H00FF08&}( PS: 他在说 java/go/c# 这种领导拍屁股想出来的语言么？)
Dialogue: 0,1:09:23.28,1:09:28.77,Default,,0000,0000,0000,,this idea, that you look for problems that fit your tool is wrong.
Dialogue: 0,1:09:28.77,1:09:30.34,Default,,0000,0000,0000,,so we did the other way around.
Dialogue: 0,1:09:30.34,1:09:36.46,Default,,0000,0000,0000,,all of the work on concept lite is done on back applications and find how we can support it.
Dialogue: 0,1:09:36.91,1:09:40.24,Default,,0000,0000,0000,,and we don't have the semantic parts
Dialogue: 0,1:09:40.24,1:09:40.86,Default,,0000,0000,0000,,because ...
Dialogue: 0,1:09:40.86,1:09:47.23,Default,,0000,0000,0000,,we consider that ... would be too much to handle just now.
Dialogue: 0,1:09:47.56,1:09:52.25,Default,,0000,0000,0000,,we don't see problems that checking template in isolation but we don't do it.
Dialogue: 0,1:09:52.57,1:09:55.95,Default,,0000,0000,0000,,that is, we check the use of a template
Dialogue: 0,1:09:55.95,1:10:02.79,Default,,0000,0000,0000,,if a template specify to require something, we assume that the implementation will stick to that contract.
Dialogue: 0,1:10:02.79,1:10:04.53,Default,,0000,0000,0000,,we don't actually verify it.
Dialogue: 0,1:10:04.66,1:10:07.86,Default,,0000,0000,0000,,we think it can be verified but you have to be very careful.
Dialogue: 0,1:10:07.96,1:10:09.99,Default,,0000,0000,0000,,those of you who has ...
Dialogue: 0,1:10:10.06,1:10:10.93,Default,,0000,0000,0000,,err...
Dialogue: 0,1:10:10.93,1:10:16.40,Default,,0000,0000,0000,,have work with strict functional languages like Haskell
Dialogue: 0,1:10:16.40,1:10:26.43,Default,,0000,0000,0000,,we know it's really hard to debug, because you make some slight change to the implementation, like insert the extern model printf, the interface change, and every thing has to change.
Dialogue: 0,1:10:26.58,1:10:27.95,Default,,0000,0000,0000,,that is painful.
Dialogue: 0,1:10:27.95,1:10:33.68,Default,,0000,0000,0000,,we didn't want to go that, we need more work more experience before we standardized something like that.
Dialogue: 0,1:10:33.68,1:10:37.10,Default,,0000,0000,0000,,and we don't actually use requires that much.
Dialogue: 0,1:10:37.85,1:10:40.34,Default,,0000,0000,0000,,overloading is fairly easy.
Dialogue: 0,1:10:40.34,1:10:45.39,Default,,0000,0000,0000,,we have two versions of find, one for sequences and one for associative containers.
Dialogue: 0,1:10:45.60,1:10:47.58,Default,,0000,0000,0000,,if I take a vector or multiset
Dialogue: 0,1:10:47.58,1:10:49.52,Default,,0000,0000,0000,,I try to find something in the vector
Dialogue: 0,1:10:49.65,1:10:53.73,Default,,0000,0000,0000,,it will find the first overload and go and search along.
Dialogue: 0,1:10:53.73,1:10:57.51,Default,,0000,0000,0000,,for the second one, it will notice it is an associative container
Dialogue: 0,1:10:57.51,1:11:07.62,Default,,0000,0000,0000,,it will pick the second one , and it will do the search in the associative container, which is certainly not a liner search through it. that works.
Dialogue: 0,1:11:08.11,1:11:12.36,Default,,0000,0000,0000,,and if you look at it, the overloading is based on predicates.
Dialogue: 0,1:11:12.36,1:11:17.38,Default,,0000,0000,0000,,that means, we don't have a notion of a hierarchy refinement  thing.
Dialogue: 0,1:11:17.38,1:11:23.77,Default,,0000,0000,0000,,we simply take the predicates, flap them out as boolean expression
Dialogue: 0,1:11:24.03,1:11:26.95,Default,,0000,0000,0000,,see which boolean expression is subset of t other.
Dialogue: 0,1:11:27.19,1:11:32.90,Default,,0000,0000,0000,,if it does, we have refinement relation. if not , we just see what works.
Dialogue: 0,1:11:32.90,1:11:36.27,Default,,0000,0000,0000,,if it calls one function and not the other, it's fine.
Dialogue: 0,1:11:36.54,1:11:40.65,Default,,0000,0000,0000,,if it calls, it can call two, we pick the more specialized one
Dialogue: 0,1:11:41.03,1:11:48.03,Default,,0000,0000,0000,,if we can call two, an they are not specialization of each other, it's an ambiguity error
Dialogue: 0,1:11:48.47,1:11:49.99,Default,,0000,0000,0000,,that's the whole set or rules.
Dialogue: 0,1:11:50.21,1:11:55.93,Default,,0000,0000,0000,,it's just do event diagram, that ont that ont and that one , finished.
Dialogue: 0,1:11:56.19,1:12:02.43,Default,,0000,0000,0000,,so we compute what the ambiguity resolution it suppose to be
Dialogue: 0,1:12:02.60,1:12:04.01,Default,,0000,0000,0000,,and the classic example here.
Dialogue: 0,1:12:04.01,1:12:05.02,Default,,0000,0000,0000,,we take advance.
Dialogue: 0,1:12:05.45,1:12:15.09,Default,,0000,0000,0000,,here is advance that take an input iterator,  here is advance that take a bidirectional iterator, and here is advance that take a random access iterator
Dialogue: 0,1:12:15.34,1:12:21.06,Default,,0000,0000,0000,,the are implemented differently. and we are quite capable of piking the right one in all cases
Dialogue: 0,1:12:21.77,1:12:23.64,Default,,0000,0000,0000,,ok, how did we define it?
Dialogue: 0,1:12:23.64,1:12:33.33,Default,,0000,0000,0000,,well that just bool expression so you write bool expressions, bool expressions get tedious so you write functions that are return booleans, this all work in.
Dialogue: 0,1:12:33.76,1:12:40.89,Default,,0000,0000,0000,,to help you write, there is "required(expression)" that takes a expression
Dialogue: 0,1:12:40.89,1:12:46.02,Default,,0000,0000,0000,,if it is valid expression then return true, if not, it just return false
Dialogue: 0,1:12:46.02,1:12:48.42,Default,,0000,0000,0000,,this will suppose to be implementation details
Dialogue: 0,1:12:48.42,1:12:53.42,Default,,0000,0000,0000,,but everybody scream, they want it,  so this not part of the technical specification.
Dialogue: 0,1:12:54.02,1:13:03.08,Default,,0000,0000,0000,,and to recognize them syntactically, I will show you why we need to do that, we call them concept rather than constexpr.
Dialogue: 0,1:13:03.20,1:13:07.54,Default,,0000,0000,0000,,we simply take the work constexpr out, and put concept in.
Dialogue: 0,1:13:07.70,1:13:10.21,Default,,0000,0000,0000,,so that they are the same thing except for the syntax analyzer.
Dialogue: 0,1:13:11.10,1:13:13.98,Default,,0000,0000,0000,,how do we get to sort a container?
Dialogue: 0,1:13:15.96,1:13:20.13,Default,,0000,0000,0000,,basically, it's a terse notation what I call it.
Dialogue: 0,1:13:20.32,1:13:26.97,Default,,0000,0000,0000,,it means, sorting a container means sorting a type that meets the container requirements.
Dialogue: 0,1:13:27.92,1:13:29.07,Default,,0000,0000,0000,,and basically
Dialogue: 0,1:13:29.07,1:13:36.21,Default,,0000,0000,0000,,that again means give me a type, check the containers requirements on it, and use that type as argument.
Dialogue: 0,1:13:36.34,1:13:38.45,Default,,0000,0000,0000,,so basically these three ... I ...
Dialogue: 0,1:13:38.45,1:13:39.09,Default,,0000,0000,0000,,... for example ...
Dialogue: 0,1:13:39.09,1:13:43.61,Default,,0000,0000,0000,,I use the underscore underscore to show that it's actually not a
Dialogue: 0,1:13:43.61,1:13:48.10,Default,,0000,0000,0000,,it'a generated name that you can't actually refer to
Dialogue: 0,1:13:48.31,1:13:51.43,Default,,0000,0000,0000,,but this is equivalent.
Dialogue: 0,1:13:51.43,1:13:56.48,Default,,0000,0000,0000,,so if you like to write out the longhand yourself, you will write something like this.
Dialogue: 0,1:13:57.26,1:14:00.27,Default,,0000,0000,0000,,it will assert that it's a container. and we do the stuff
Dialogue: 0,1:14:00.38,1:14:04.70,Default,,0000,0000,0000,,so, this is part of this idea of making simple things simple
Dialogue: 0,1:14:05.35,1:14:10.26,Default,,0000,0000,0000,,this is the simplest algorithms work really nicely for this ?? .
Dialogue: 0,1:14:10.26,1:14:13.15,Default,,0000,0000,0000,,and it looks just like our traditional functions.
Dialogue: 0,1:14:13.15,1:14:16.29,Default,,0000,0000,0000,,so sort , sorts, no .. sorry,
Dialogue: 0,1:14:17.03,1:14:22.72,Default,,0000,0000,0000,,square root(sqrt), take a square root  of something that can behave like a double.
Dialogue: 0,1:14:23.80,1:14:25.22,Default,,0000,0000,0000,,and include integers.
Dialogue: 0,1:14:25.66,1:14:36.63,Default,,0000,0000,0000,,basically it equals the square root function has been specified with the predicate that it's argument has be able to behave like a double.
Dialogue: 0,1:14:26.40,1:14:30.51,Default,,0000,0000,0000,,\{think of the sort function .. as been the \} <-- 多说的废话
Dialogue: 0,1:14:38.45,1:14:48.36,Default,,0000,0000,0000,,so, we do the same thing more general, with  sort, it requires something that can behave like a container. and we have these predicate for testing it.
Dialogue: 0,1:14:49.48,1:14:52.22,Default,,0000,0000,0000,,now we back to where I want it to be.
Dialogue: 0,1:14:52.38,1:14:52.91,Default,,0000,0000,0000,,here
Dialogue: 0,1:14:52.91,1:15:00.04,Default,,0000,0000,0000,,sqrt doubles, this works, it doesn't. sort containers  , this works, and this doesn't
Dialogue: 0,1:15:00.04,1:15:03.13,Default,,0000,0000,0000,,and we get one liner message there.
Dialogue: 0,1:15:03.48,1:15:12.94,Default,,0000,0000,0000,,so, we can start thinking about generic function exactly like other functions, and you know they look like other functions.
Dialogue: 0,1:15:14.87,1:15:18.53,Default,,0000,0000,0000,,now going form the simplest cases to the the more complicated one.
Dialogue: 0,1:15:18.63,1:15:22.44,Default,,0000,0000,0000,,lets see that this actually how well handle the complicated one
Dialogue: 0,1:15:22.44,1:15:26.90,Default,,0000,0000,0000,,here is ... em.... here is merge.
Dialogue: 0,1:15:28.05,1:15:29.45,Default,,0000,0000,0000,,it's a ..
Dialogue: 0,1:15:30.35,1:15:32.73,Default,,0000,0000,0000,,yeah, it's merge, right there
Dialogue: 0,1:15:33.08,1:15:34.84,Default,,0000,0000,0000,,it's pretty ugly.
Dialogue: 0,1:15:35.14,1:15:38.52,Default,,0000,0000,0000,,it has given many people headaches, including me.
Dialogue: 0,1:15:38.93,1:15:42.67,Default,,0000,0000,0000,,if you think that's too easy, try accumulate().
Dialogue: 0,1:15:42.80,1:15:43.76,Default,,0000,0000,0000,,it's even worse.
Dialogue: 0,1:15:44.11,1:15:45.34,Default,,0000,0000,0000,,so
Dialogue: 0,1:15:45.34,1:15:49.48,Default,,0000,0000,0000,,we need to get this stuff under control. and we look that's ....
Dialogue: 0,1:15:51.83,1:16:00.02,Default,,0000,0000,0000,,that's just too ugly , too easy to make mistakes, too repetitive , ah, not good enough. so let's try simplify it a bit.
Dialogue: 0,1:16:00.29,1:16:04.20,Default,,0000,0000,0000,,we can say forward iterator for , forward iterator for to be used as shorthand.
Dialogue: 0,1:16:04.44,1:16:14.77,Default,,0000,0000,0000,,and we use one requires that predicates these three and check the connections between them.
Dialogue: 0,1:16:15.17,1:16:23.92,Default,,0000,0000,0000,,for complicated algorithm that take many arguments, very often you have predicates that takes all of these arguments and works some relation between them.
Dialogue: 0,1:16:24.55,1:16:30.50,Default,,0000,0000,0000,,it's a matter fact, i don't think you'll have a good algorithm where there was no relationship at all.
Dialogue: 0,1:16:30.89,1:16:33.44,Default,,0000,0000,0000,,at least it's rare and these domain.
Dialogue: 0,1:16:33.76,1:16:44.99,Default,,0000,0000,0000,,and so, this is quite readable, and we are try to attack this problem. if that's your solution, we know what your problem is. you have to simplify. we can simplify even further.
Dialogue: 0,1:16:45.57,1:16:50.58,Default,,0000,0000,0000,,I just said we had a concept that test that three types for mergeable.
Dialogue: 0,1:16:50.74,1:16:54.40,Default,,0000,0000,0000,,so we have a little notation using ??? it says
Dialogue: 0,1:16:54.40,1:16:57.21,Default,,0000,0000,0000,,give me three types that meet this.
Dialogue: 0,1:16:57.49,1:17:00.98,Default,,0000,0000,0000,,\Nand here are the way i'm using these three types.
Dialogue: 0,1:17:01.39,1:17:09.65,Default,,0000,0000,0000,,we just rap the whole thing up and just say, give me a set of types, that meets my requirements.
Dialogue: 0,1:17:09.85,1:17:14.58,Default,,0000,0000,0000,,so that introduce three names in a scope
Dialogue: 0,1:17:14.58,1:17:17.03,Default,,0000,0000,0000,,"For" "For2" and "Out" which will using here.
Dialogue: 0,1:17:17.39,1:17:27.95,Default,,0000,0000,0000,,and it says that once you give me that in a call, I'll execute the predicate "mergeable" on them to see whether it works.
Dialogue: 0,1:17:28.67,1:17:33.96,Default,,0000,0000,0000,,and, that's the way it looks.
Dialogue: 0,1:17:34.23,1:17:44.13,Default,,0000,0000,0000,,obviously, we take three type names, the first one have to be forward iterator, the second one have to be forward iterator too, not necessary the same forward iterator type.
Dialogue: 0,1:17:44.44,1:17:52.20,Default,,0000,0000,0000,,and then we have output iterator, we have assignable requirements and comparable requirements. that's it! just the predicate.
Dialogue: 0,1:17:53.90,1:18:00.44,Default,,0000,0000,0000,,so, this sounds very good.
Dialogue: 0,1:18:00.91,1:18:04.22,Default,,0000,0000,0000,,we are of course not finished.
Dialogue: 0,1:18:04.34,1:18:08.28,Default,,0000,0000,0000,,that is, there are mush more we can do to improve c++.
Dialogue: 0,1:18:08.28,1:18:16.63,Default,,0000,0000,0000,,so let me finish off by looking a bit on the challenges that's facing us. there are many and complicated.
Dialogue: 0,1:18:17.01,1:18:23.46,Default,,0000,0000,0000,,those of you who are to take an Ancient Greek knows this is one of the labors Hercules(Heracles). he is trying to kill a hydra.
Dialogue: 0,1:18:24.03,1:18:25.76,Default,,0000,0000,0000,,very hard task.
Dialogue: 0,1:18:26.08,1:18:27.23,Default,,0000,0000,0000,,so
Dialogue: 0,1:18:27.23,1:18:29.94,Default,,0000,0000,0000,,c++ challenges.
Dialogue: 0,1:18:30.62,1:18:40.95,Default,,0000,0000,0000,,so, we want to make a better languages , and we also want to convince programmers that the new stuff actually worth well.
Dialogue: 0,1:18:41.42,1:18:47.21,Default,,0000,0000,0000,,and that's relatively easy for actually getting people to use in large code bases.
Dialogue: 0,1:18:47.21,1:18:54.00,Default,,0000,0000,0000,,but. we first have to improve the languages and then we have convince people that use worth well.
Dialogue: 0,1:18:54.00,1:19:04.24,Default,,0000,0000,0000,,and then we can start seeing the practical problems of introducing it into the existing code bases that doesn't have it.
Dialogue: 0,1:19:04.44,1:19:10.14,Default,,0000,0000,0000,,I refer to that as source code rejuvenation, and I think that is going to be an important issue.
Dialogue: 0,1:19:11.01,1:19:12.40,Default,,0000,0000,0000,,so basically
Dialogue: 0,1:19:12.93,1:19:14.88,Default,,0000,0000,0000,,what ever we do  to the language
Dialogue: 0,1:19:14.88,1:19:18.07,Default,,0000,0000,0000,,or what ever we do to change the implementations
Dialogue: 0,1:19:18.39,1:19:22.60,Default,,0000,0000,0000,,we can't eliminate the c++ major strength
Dialogue: 0,1:19:22.78,1:19:30.39,Default,,0000,0000,0000,,that is a lot of people has a solutions that ends up been worse that the problem for a large number of people.
Dialogue: 0,1:19:31.10,1:19:34.28,Default,,0000,0000,0000,,compatibility is a feature in itself.
Dialogue: 0,1:19:34.33,1:19:39.60,Default,,0000,0000,0000,,that means that ugly things will not go away even when you provide good alternatives.
Dialogue: 0,1:19:39.60,1:19:43.90,Default,,0000,0000,0000,,we just have to get people to use the good alternatives where they can.
Dialogue: 0,1:19:44.09,1:19:46.35,Default,,0000,0000,0000,,so compatibility is necessary.
Dialogue: 0,1:19:46.35,1:19:57.27,Default,,0000,0000,0000,,performance, uncompromising , portability where appropriate , and we would like to increase, not restrict, the application areas.
Dialogue: 0,1:19:57.50,1:20:04.70,Default,,0000,0000,0000,,if we could restrict the ranges of application , we could be get a ??? language.
Dialogue: 0,1:20:04.74,1:20:05.04,Default,,0000,0000,0000,,but
Dialogue: 0,1:20:05.64,1:20:11.74,Default,,0000,0000,0000,,actually there is a crew by me from about 1984, then even I can decide a ??? language.
Dialogue: 0,1:20:12.26,1:20:14.53,Default,,0000,0000,0000,,that just wasn't the exercise
Dialogue: 0,1:20:14.53,1:20:21.67,Default,,0000,0000,0000,,it was not the aim of those that use by most useful language for more people for more application areas.
Dialogue: 0,1:20:21.67,1:20:25.86,Default,,0000,0000,0000,,and I think that is very well worth pursuing.
Dialogue: 0,1:20:26.39,1:20:27.80,Default,,0000,0000,0000,,so the challenge is
Dialogue: 0,1:20:27.80,1:20:32.56,Default,,0000,0000,0000,,I would like to close more type loopholes
Dialogue: 0,1:20:33.29,1:20:36.62,Default,,0000,0000,0000,,we need to address concurrent programming
Dialogue: 0,1:20:36.62,1:20:48.26,Default,,0000,0000,0000,,we need some thing that's higher level than the threads, locks style programming which is universal necessary
Dialogue: 0,1:20:48.26,1:20:51.49,Default,,0000,0000,0000,,and about the worse way writing concurrency system that I know of.
Dialogue: 0,1:20:51.76,1:20:55.92,Default,,0000,0000,0000,,we need to build libraries that provide higher-level models
Dialogue: 0,1:20:56.39,1:20:58.91,Default,,0000,0000,0000,,we want to simplify generic programming
Dialogue: 0,1:20:59.28,1:21:02.16,Default,,0000,0000,0000,,I'm looking at concepts
Dialogue: 0,1:21:02.16,1:21:03.61,Default,,0000,0000,0000,,we should ..
Dialogue: 0,1:21:03.61,1:21:08.09,Default,,0000,0000,0000,,I means some of us have them today, but we need have them all next year.
Dialogue: 0,1:21:09.72,1:21:13.35,Default,,0000,0000,0000,,and we want to simplify programming using class hierarchies
Dialogue: 0,1:21:13.35,1:21:23.62,Default,,0000,0000,0000,,I've been doing some work on  ..... multimethods and functional style ... pattern matching
Dialogue: 0,1:21:23.91,1:21:30.21,Default,,0000,0000,0000,,some of it is available on my homepage, on the publications and software also available.
Dialogue: 0,1:21:30.57,1:21:37.79,Default,,0000,0000,0000,,but that's the research work, but I hope some of it gets into the language if not now then later.
Dialogue: 0,1:21:37.79,1:21:41.67,Default,,0000,0000,0000,,you have to think in-long-term in this kinds of stuff.
Dialogue: 0,1:21:42.25,1:21:48.93,Default,,0000,0000,0000,,some times, you have to sort of imagine what the world would like in ten years, and try to get there.
Dialogue: 0,1:21:49.42,1:22:00.51,Default,,0000,0000,0000,,I suppose to thinking , oh ,dear, it will take more than a year, I can't do it. the next quarter is essential ..  on  that kind of thing. we have to have some longer term thinking.
Dialogue: 0,1:22:00.86,1:22:02.78,Default,,0000,0000,0000,,let's see.
Dialogue: 0,1:22:02.89,1:22:08.63,Default,,0000,0000,0000,,better support for ... object oriented generic programming .. get back to that.
Dialogue: 0,1:22:08.63,1:22:17.07,Default,,0000,0000,0000,,but I don't like the way the community some time fold into different and waring camps when they don't have an need to.
Dialogue: 0,1:22:17.07,1:22:22.06,Default,,0000,0000,0000,,we have to support, combinations of programming styles.
Dialogue: 0,1:22:22.29,1:22:26.21,Default,,0000,0000,0000,,we have to make exception usable for real time project.
Dialogue: 0,1:22:26.21,1:22:34.06,Default,,0000,0000,0000,,one of the things I've said about is that exceptions are not used for hard real time, it can be used for soft real time.
Dialogue: 0,1:22:34.14,1:22:36.89,Default,,0000,0000,0000,,and the reason is very simple.
Dialogue: 0,1:22:37.02,1:22:44.24,Default,,0000,0000,0000,,it is, we don't have tools that allow us to estimate how long it takes to recover from an error when exception is thrown
Dialogue: 0,1:22:44.24,1:22:45.84,Default,,0000,0000,0000,,the tools don't exist
Dialogue: 0,1:22:45.84,1:22:49.67,Default,,0000,0000,0000,,I want to build it from 5 years ago but somehow I never get around to it.
Dialogue: 0,1:22:49.81,1:22:52.17,Default,,0000,0000,0000,,been an university students .
Dialogue: 0,1:22:52.34,1:22:56.79,Default,,0000,0000,0000,,it became too difficult to work on a problem just because it all to be solved.
Dialogue: 0,1:22:57.07,1:23:01.75,Default,,0000,0000,0000,,it alse has to be publishable  teachable and fashionable
Dialogue: 0,1:23:02.10,1:23:05.19,Default,,0000,0000,0000,,but we need to make exceptions more usable
Dialogue: 0,1:23:06.13,1:23:10.01,Default,,0000,0000,0000,,and we have to deal with multiple address spaces eventually.
Dialogue: 0,1:23:10.46,1:23:18.90,Default,,0000,0000,0000,,the notion that everything works in a single address space is ... it's creaking , it's difficult.
Dialogue: 0,1:23:19.25,1:23:26.22,Default,,0000,0000,0000,,we get these big memories with lots of cores lots of things, but they are uniform any more.
Dialogue: 0,1:23:27.41,1:23:33.47,Default,,0000,0000,0000,,different memories takes different time to use in such way. I think we need to think about that.
Dialogue: 0,1:23:33.65,1:23:36.83,Default,,0000,0000,0000,,we want more domain specific libraries
Dialogue: 0,1:23:37.03,1:23:42.22,Default,,0000,0000,0000,,and we want to develop a better specification of c++
Dialogue: 0,1:23:42.31,1:23:48.48,Default,,0000,0000,0000,,I think English text is.. err, is ,,, maxing out in terms of what we can handle.
Dialogue: 0,1:23:49.23,1:23:53.40,Default,,0000,0000,0000,,finally I just do a little rant.
Dialogue: 0,1:23:53.40,1:23:57.09,Default,,0000,0000,0000,,I really dislike the word paradigms.
Dialogue: 0,1:23:57.67,1:24:08.58,Default,,0000,0000,0000,,it was invented by coon and imply some superiority of one paradigms over another. and things changes, everything changes, nor the older stuff became bad.
Dialogue: 0,1:24:10.38,1:24:19.72,Default,,0000,0000,0000,,Kristen Nygaard said, you know, addiction didn't actually become useless just because we invented multiplication
Dialogue: 0,1:24:20.44,1:24:22.95,Default,,0000,0000,0000,,nothing was over turned
Dialogue: 0,1:24:22.95,1:24:27.59,Default,,0000,0000,0000,,you incorporate the old stuff, maybe you have to re-phrase the old stuff
Dialogue: 0,1:24:27.59,1:24:31.36,Default,,0000,0000,0000,,newton mechanism just not disappear just because of Einstein
Dialogue: 0,1:24:31.96,1:24:37.09,Default,,0000,0000,0000,,it became special case, actually a very useful special case.
Dialogue: 0,1:24:37.16,1:24:48.95,Default,,0000,0000,0000,,similarly, I would like to see OOP, GP, and conventional programming just as differential aspects that you can use in combinations
Dialogue: 0,1:24:49.26,1:24:59.35,Default,,0000,0000,0000,,and I want be able to develop rules for how you do things that doesn't chock in terms of these paradigms which might become semi religions.
Dialogue: 0,1:24:59.85,1:25:05.72,Default,,0000,0000,0000,,and the focus has been on  language features
Dialogue: 0,1:25:05.72,1:25:08.65,Default,,0000,0000,0000,,do I write templates do I write virtual functions
Dialogue: 0,1:25:08.65,1:25:12.70,Default,,0000,0000,0000,,that's  incomplete senses.
Dialogue: 0,1:25:12.85,1:25:18.66,Default,,0000,0000,0000,,so I think it makes harms, it makes things complicated, it grades bad code
Dialogue: 0,1:25:18.80,1:25:30.69,Default,,0000,0000,0000,,and people write code for instance, if they believe object oriented is right, they are write generic code using interfaces in virtual functions, which is less convince than templates and run much slow.
Dialogue: 0,1:25:31.78,1:25:43.45,Default,,0000,0000,0000,,and similarly you can have people that so believing in generic programming that they make everything into statically resolved overloading
Dialogue: 0,1:25:43.45,1:25:50.52,Default,,0000,0000,0000,,and they should have build hierarchy and dynamic solution will much simple and easier to debug and document.
Dialogue: 0,1:25:50.87,1:25:52.93,Default,,0000,0000,0000,,so here is an example of what I mean.
Dialogue: 0,1:25:52.93,1:25:55.67,Default,,0000,0000,0000,,I want to draw all elements in a container.
Dialogue: 0,1:25:57.51,1:26:05.40,Default,,0000,0000,0000,,And I want that container to have value type that is the type of the element to be pointers to shapes.
Dialogue: 0,1:26:06.36,1:26:13.73,Default,,0000,0000,0000,,fine, and then I want to for each elements in the container, I want to call draw
Dialogue: 0,1:26:14.89,1:26:21.56,Default,,0000,0000,0000,,now, this is the generalization of the classical object oriented programming : draw all shapes.
Dialogue: 0,1:26:21.67,1:26:22.84,Default,,0000,0000,0000,,that was first on..
Dialogue: 0,1:26:22.98,1:26:25.66,Default,,0000,0000,0000,,way back in 67..
Dialogue: 0,1:26:25.66,1:26:28.07,Default,,0000,0000,0000,,for useful paradigm.
Dialogue: 0,1:26:28.83,1:26:31.77,Default,,0000,0000,0000,,before they have screens that could do this kinds of things.
Dialogue: 0,1:26:31.77,1:26:35.33,Default,,0000,0000,0000,,so this is an old program. it's obviously object oriented code.
Dialogue: 0,1:26:35.58,1:26:39.46,Default,,0000,0000,0000,,also see here, it's clearly hierarchy of shapes.
Dialogue: 0,1:26:41.66,1:26:46.19,Default,,0000,0000,0000,,and there's a virtual function that dispatches to the right kinds of shape. this is object oriented code.
Dialogue: 0,1:26:46.71,1:26:48.44,Default,,0000,0000,0000,,obviously it's generic
Dialogue: 0,1:26:48.44,1:26:49.30,Default,,0000,0000,0000,,look
Dialogue: 0,1:26:49.30,1:26:52.40,Default,,0000,0000,0000,,it is parametrized on the kinds of container
Dialogue: 0,1:26:52.58,1:26:54.62,Default,,0000,0000,0000,,and you want to do the same
Dialogue: 0,1:26:54.62,1:27:00.12,Default,,0000,0000,0000,,to ..  element type ..to that ... and you call for_each algorithm.
Dialogue: 0,1:27:00.12,1:27:03.86,Default,,0000,0000,0000,,it's cleanly cleanly generic programming.
Dialogue: 0,1:27:04.10,1:27:07.39,Default,,0000,0000,0000,,but it's also very ordinary programming
Dialogue: 0,1:27:07.55,1:27:10.56,Default,,0000,0000,0000,,I just want to draw everything in a container.
Dialogue: 0,1:27:10.87,1:27:14.13,Default,,0000,0000,0000,,and I just call a couple of functions on them
Dialogue: 0,1:27:14.34,1:27:20.02,Default,,0000,0000,0000,,it happens to be a lambda, but .. hey, it's just a peace of code that's called.
Dialogue: 0,1:27:20.45,1:27:30.79,Default,,0000,0000,0000,,so, I don't believe that you can creditably claim that this one is one and not the other two.
Dialogue: 0,1:27:31.51,1:27:36.48,Default,,0000,0000,0000,,it's all three and integrate rather nicely, we have to work on this integration.
Dialogue: 0,1:27:38.39,1:27:42.47,Default,,0000,0000,0000,,ok, we reach the Q&A time
Dialogue: 0,1:27:43.24,1:27:49.25,Default,,0000,0000,0000,,and .. I'm not sure.. do we have some microphones that people can use?
Dialogue: 0,1:27:49.25,1:27:54.74,Default,,0000,0000,0000,,because I barely see people in the back, I certainly can't hear you out there.
Dialogue: 0,1:28:01.92,1:28:03.18,Default,,0000,0000,0000,,so any questions?
Dialogue: 0,1:28:03.18,1:28:06.98,Default,,0000,0000,0000,,this one up there. ah.
Dialogue: 0,1:28:06.98,1:28:08.98,Default,,0000,0000,0000,,