pwb_tutorial_07_ate

#!/usr/bin/env bash

## BEGIN_DOC
## This tutorial introduces a custom Bash builtin
## to be used for the PWB` datasource: the ATE
## array table extension.
##
## This change will affect all of the steps, but
## particulary steps 2 (implement line-print
## function) and 3 (prepare data source).
## END_DOC

# 1. Enable the builtin(s)
enable pwb
#   Diff #1: enable ATE builtin, too.
enable ate

# 2. Create line-printing function
print_line()
{
    local -i index="$1"
    local data_name="$2"
    local -i chars_limit="$3"

    # Diff #2: Using ATE methods to retrieve data
    ate get_row "$data_name" "$index"
    local line="${ATE_ARRAY[0]}"

    printf "%-*s" "$chars_limit" "${line:0:$chars_limit}"
}

# 3. Get data
#    Diff #3 Using ATE methods
declare ftable
ate declare ftable 1
#   Use one of two methods to fill the ATE table:
if : ; then
    # using ATE method
    ate append_data ftable *
else
    # or writing to host array
    ate get_array_name ftable
    declare -n ftarray="$ATE_VALUE"
    ftarray=( * )
    # -n unset the nameref, leaving its source untouched:
    unset -n ftarray
fi
#  You should always 'index_rows' after changing the array
#  contents.  Neglecting this leaves new records invisible
#  when adding records, but can cause a segmentation fault
#  if array elements are removed without reindexing the rows.
ate index_rows ftable

#   Diff #4: use ATE methods to get table data count
declare -i file_count
ate get_row_count ftable -v file_count

#4 Declare the pwb handle
declare phandle
pwb declare phandle ftable "$file_count" print_line

#5 Start the interaction
pwb init
pwb start phandle
pwb restore