Remove six compatibility library

This library is necessary only for Python 2 support, and now that we
have dropped support for 2.7, we don't need it anymore.

Signed-off-by: Gus Monod <[email protected]>

comdb2/__init__.py

@@ -12,7 +12,7 @@
 """This package provides Python interfaces to Comdb2 databases.
 
 Two different Python submodules are provided for interacting with Comdb2
-databases.  Both submodules work from Python 2.7+ and from Python 3.5+.
+databases.  Both submodules work from Python 3.6.
 
 `comdb2.dbapi2` provides an interface that conforms to `the Python Database API
 Specification v2.0 <https://www.python.org/dev/peps/pep-0249/>`_.  If you're

comdb2/_ccdb2.pyx

@@ -22,7 +22,6 @@ from cpython.mem cimport PyMem_Malloc, PyMem_Free
 import datetime
 
 from pytz import timezone, UTC
-import six
 
 from ._cdb2_types import Error, Effects, DatetimeUs
 from . cimport _cdb2api as lib
@@ -113,7 +112,7 @@ cdef class _ParameterValue(object):
                 self.size = 0
                 self.data = NULL
                 return
-            elif isinstance(obj, six.integer_types):
+            elif isinstance(obj, int):
                 self.type = lib.CDB2_INTEGER
                 self.owner = None
                 self.size = sizeof(long long)
@@ -167,7 +166,7 @@ cdef class _ParameterValue(object):
                 param_name,
                 exc_desc,
             )
-            six.raise_from(Error(lib.CDB2ERR_CONV_FAIL, errmsg), exc)
+            raise Error(lib.CDB2ERR_CONV_FAIL, errmsg) from exc
         else:
             errmsg = "Can't map %s value %r for parameter '%s' to a Comdb2 type" % (
                 type(obj).__name__,
@@ -248,7 +247,7 @@ cdef _column_value(lib.cdb2_hndl_tp *hndl, int col):
 
     if exc is not None:
         errmsg += _describe_exception(exc)
-        six.raise_from(Error(lib.CDB2ERR_CONV_FAIL, errmsg), exc)
+        raise Error(lib.CDB2ERR_CONV_FAIL, errmsg) from exc
     else:
         errmsg += "Unsupported column type"
         raise Error(lib.CDB2ERR_NOTSUPPORTED, errmsg)
@@ -289,7 +288,7 @@ cdef class _Cursor(object):
                 ret = self.row_class(ret)
             except Exception as e:
                 errmsg = "Instantiating row failed: " + _describe_exception(e)
-                six.raise_from(Error(lib.CDB2ERR_UNKNOWN, errmsg), e)
+                raise Error(lib.CDB2ERR_UNKNOWN, errmsg) from e
         return ret
 
 
@@ -393,7 +392,7 @@ cdef class Handle(object):
                 row_class = self._row_factory(self.column_names())
             except Exception as e:
                 errmsg = "row_factory call failed: " + _describe_exception(e)
-                six.raise_from(Error(lib.CDB2ERR_UNKNOWN, errmsg), e)
+                raise Error(lib.CDB2ERR_UNKNOWN, errmsg) from e
 
         cdef _Cursor ret = _Cursor.__new__(_Cursor)
         ret.handle = self

comdb2/_cdb2_types.py

@@ -11,7 +11,6 @@
 
 from collections import namedtuple
 from datetime import datetime
-import six
 
 __name__ = 'comdb2.cdb2'
 

comdb2/cdb2.py

@@ -112,8 +112,8 @@
 NULL           ``None``
 integer        `int`
 real           `float`
-blob           `six.binary_type` (aka `bytes` in Python 3, ``str`` in Python 2)
-text           `six.text_type` (aka `str` in Python 3, ``unicode`` in Python 2)
+blob           `bytes`
+text           `str`
 datetime       `datetime.datetime`
 datetimeus     `DatetimeUs`
 ============   ================================================================

comdb2/dbapi2.py

@@ -138,8 +138,8 @@
 NULL           ``None``
 integer        `int`
 real           `float`
-blob           `six.binary_type` (aka `bytes` in Python 3, ``str`` in Python 2)
-text           `six.text_type` (aka `str` in Python 3, ``unicode`` in Python 2)
+blob           `bytes`
+text           `str`
 datetime       `datetime.datetime`
 datetimeus     `DatetimeUs`
 ============   ================================================================
@@ -245,7 +245,6 @@
 import weakref
 import datetime
 import re
-import six
 
 from . import cdb2
 
@@ -297,7 +296,7 @@
     \s*           # then skip over any whitespace
     (\w+)         # and capture the first word
     """,
-    re.VERBOSE | re.DOTALL | (0 if six.PY2 else re.ASCII),
+    re.VERBOSE | re.DOTALL | re.ASCII,
 )
 _VALID_SP_NAME = re.compile(r'^[A-Za-z0-9_.]+$')
 
@@ -349,10 +348,7 @@ def _binary(string):
 TimestampFromTicks = Timestamp.fromtimestamp
 TimestampUsFromTicks = TimestampUs.fromtimestamp
 
-try:
-    UserException = StandardError  # Python 2
-except NameError:
-    UserException = Exception      # Python 3
+UserException = Exception
 
 
 class Error(UserException):

docs/conf.py

@@ -261,8 +261,7 @@
 
 
 # Example configuration for intersphinx: refer to the Python standard library.
-intersphinx_mapping = {'python': ('https://docs.python.org/3', None),
-                       'six': ('https://six.readthedocs.io', None)}
+intersphinx_mapping = {'python': ('https://docs.python.org/3', None)}
 
 # Don't highlight the code for the Python standard library datetime module.
 viewcode_import = False

docs/dbapi2.rst

@@ -87,9 +87,9 @@ them if you so choose, but you are not required to.
 
     Creates an object suitable for binding as a BLOB parameter.
 
-    If the input argument was a `six.text_type` Unicode string, it is
-    encoded as a UTF-8 byte string and returned.  Otherwise, the input
-    argument is passed to the `bytes` constructor, and the result returned.
+    If the input argument was a `str` object, it is encoded as a UTF-8 byte
+    string and returned.  Otherwise, the input argument is passed to the
+    `bytes` constructor, and the result returned.
 
     :param string: A string from which the new object is constructed
     :rtype: `bytes`

docs/tips.rst

@@ -2,10 +2,9 @@
 Best Practices, Tips, and Tricks
 ********************************
 
-#. This package uses `six.text_type` for text and `bytes` for blobs; this may
-   be surprising if you're using `str` in Python 2.  See :doc:`types` for an
-   explanation of what Python types must be used when binding parameters, and
-   what Python types will be returned for result columns.
+#. This package uses `str` for text and `bytes` for blobs. See :doc:`types` for
+   an explanation of what Python types must be used when binding parameters,
+   and what Python types will be returned for result columns.
 
    An error message saying "incompatible values from SQL blob of length 3 to
    bcstring field 'foo'" most likely means that you passed a byte string where
@@ -24,11 +23,8 @@ Best Practices, Tips, and Tricks
    a ``WHERE`` clause that you expected to match some rows will silently fail
    to match any.
 
-#. Prefer using Python 3 rather than Python 2 when possible.  The above type
-   mappings are much more intuitive in Python 3 than in Python 2.  If you can't
-   use Python 3 but are writing a new module, prefer to use ``from __future__
-   import unicode_literals`` to opt into forward compatible unicode string
-   literals (rather than the default, string literals as byte strings).
+#. The latest version of this package only supports Python 3. If you can't
+   use Python 3, make sure to use version 1.4.1 or earlier.
 
 #. The database can time out connections that have been idle for a period of
    time, and each idle connection uses some amount of resources on the database

docs/types.rst

@@ -14,8 +14,8 @@ SQL type       Python type
 NULL           ``None``
 integer        `int`
 real           `float`
-blob           `six.binary_type` (aka `bytes` in Python 3, ``str`` in Python 2)
-text           `six.text_type` (aka `str` in Python 3, ``unicode`` in Python 2)
+blob           `bytes`
+text           `str`
 datetime       `datetime.datetime`
 datetimeus     `~.cdb2.DatetimeUs`
 intervalym     not supported
@@ -47,58 +47,34 @@ represent TEXT columns.  This was chosen for maximum forward compatibility with
 Python 3, and to make it easier to write code that will work identically in
 both languages.  This decision has many important ramifications.
 
-#.  In Python 2, ``'foo'`` is the wrong type for binding a ``cstring`` column.
-    You instead need to use a Unicode literal like ``u'foo'``.
-    Alternately, you can make all string literals in your module be Unicode
-    literals by default by doing::
+#.  If you have a variable of type `bytes` and you want to pass it to the
+    database as a TEXT value, you need to convert it to a `str` using
+    `~bytes.decode`.
 
-        from __future__ import unicode_literals
-
-    .. note::
-        It's not safe to blindly do this in existing code as it changes that
-        code's behavior, and might cause problems.
-
-#.  If you have a variable  of type `six.binary_type` (byte string) and you
-    want to pass it to the database as a TEXT value, you need to convert it to
-    a `six.text_type` (Unicode) string using `~bytes.decode`.  In Python 2,
-    unless ``unicode_literals`` was imported from `__future__`, you will need to
-    do this with every string variable that you want to use as a cstring
-    column.  For example::
-
-        value = 'foo'
-        params = {'col': value.decode('utf-8')}
-        # dbapi2
-        cursor.execute("select * from tbl where col=%(col)s", params)
-        # cdb2
-        handle.execute("select * from tbl where col=@col", params)
-
-#.  TEXT columns are returned to you as `six.text_type` (Unicode) strings.
-    If you need to pass them to a library that expects `six.binary_type` (byte)
-    strings, you have to use `~str.encode`, like this::
+#.  TEXT columns are returned to you as `str` strings. If you need to pass them
+    to a library that expects `bytes` strings, you have to use `~str.encode`,
+    like this::
 
         cursor.execute("select col from tbl")
         for row in cursor:
             col = row[0]
             library_func(col.encode('utf-8'))
 
-    This may come up a lot in Python 2, where historically libraries were
-    written to expect byte strings rather than Unicode strings.
-
 #.  When a TEXT column is read back from the database, it is decoded as UTF-8.
     If your database has non-UTF-8 text in a ``cstring`` column, you need to
     cast that column from a TEXT to a BLOB in SQL when reading it out, like
     this::
 
         cursor.execute("select cast(col as blob) from tbl")
 
-    That will result in you receiving a byte string rather than a Unicode
-    string for that result column.
+    That will result in you receiving a `bytes` object rather than `str` for
+    that result column.
 
     .. note::
         ASCII is a subset of UTF-8, so this is not required for if the column
         contains plain ASCII text.
 
-#.  Likewise, when a Unicode string is sent to the database, it is encoded as
+#.  Likewise, when a `str` object is sent to the database, it is encoded as
     UTF-8.  If you need to store non-UTF-8 text in a ``cstring`` column in your
     database, you need to bind a byte string in Python land, and then cast the
     value from BLOB to TEXT in SQL.  For instance, to bind a latin1 string

setup.py

@@ -48,7 +48,7 @@ def make_static_extension(name, **kwargs):
     author='Alex Chamberlain',
     author_email='[email protected]',
     packages=['comdb2'],
-    install_requires=["six", "pytz"],
+    install_requires=["pytz"],
     extras_require={"tests": ["python-dateutil>=2.6.0", "pytest"]},
     python_requires=">=3.6",
     ext_modules=[ccdb2],

tests/test_cdb2.py

@@ -14,7 +14,6 @@
 from comdb2.factories import dict_row_factory
 from comdb2.factories import namedtuple_row_factory
 import pytest
-import six
 
 COLUMN_LIST = ("short_col u_short_col int_col u_int_col longlong_col"
                " float_col double_col byte_col byte_array_col"

tests/test_dbapi2.py

@@ -36,7 +36,6 @@
 import pytest
 import datetime
 import pytz
-import six
 from functools import partial
 
 try: