cxw42 / list-autonumbered

Automatically add sequential numbers to Perl lists while creating them

List::AutoNumbered - Add sequential numbers to lists while creating them

This module adds sequential numbers to lists of lists so you don't have to type all the numbers. Its original use case was for adding line numbers to lists of testcases. For example:

use List::AutoNumbered;                             # line 1
my $list = List::AutoNumbered->new(__LINE__);       # line 2
$list->load("a")->                                  # line 3
    ("b")                                           # line 4
    ("c")                                           # line 5
    ("d");                                          # line 6

# Now $list->arr is [ [3,"a"], [4,"b"], [5,"c"], [6,"d"] ]
# and @$list is ( [3,"a"] ... ).

In general, you can pass any number to the constructor. For example:

use List::AutoNumbered;
use Test::More tests => 1;

my $list = List::AutoNumbered->new;     # First entry will be number 1
$list->load("a")->      # Yes, trailing arrow
    ("b")               # Magic!  Don"t need any more arrows!
    ("c")
    ("d");

is_deeply($list->arr, [
    [1, "a"], [2, "b"], [3, "c"], [4, "d"]
]);     # Yes, it is!

METHODS

new

Constructor. Basic usage options:

$list = List::AutoNumbered->new();      # first list item is number 1
$list = List::AutoNumbered->new($num);  # first list item is $num+1
$list = List::AutoNumbered->new(-at => $num);   # ditto

Each successive element will have the next number, unless you say otherwise (e.g., using LSKIP()). Specifically, the first item in the list will be numbered one higher than the number passed to the List::AutoNumbered constructor.

Constructor parameters are processed using Getargs::Mixed, so positional and named parameters are both OK.

The how function

You can give the constructor a "how" function that will make the list entry for a single load() or add() call:

$list = List::AutoNumbered->new(-how => sub { @_ });
    # Jam everything together to make a flat array
$list = List::AutoNumbered->new(41, sub { @_ });
    # Positional is OK, too.

The how function is called as how($num, @data). $num is the line number for load() calls, or undef for add() calls. @data is whatever data you passed to load() or add(). For example, the default how function is:

sub how {
    shift unless defined $_[0];     # add passes undef as the line number.
    [@_]                            # Wrap everything in an arrayref.
}

See t/05-custom-list-entry.t for examples of custom how functions.

size

Returns the size of the array. Like scalar @arr.

last

Returns the index of the last element in the array. Like $#array.

arr

Returns a reference to the array being built. Please do not modify this array directly until you are done loading it. List::AutoNumbered may not work if you do.

This can also be called by using the List::AutoNumbered object as an array:

my $list = List::AutoNumbered->new...;
foreach my $item (@$list) { ... }    # Instead of my $item (@{$list->arr})

last_number

Returns the current number stored by the instance. This is the number of the most recently preceding new() or load() call. This is not the number that will be given to the next record, since that depends on whether or not the next record has a skip (LSKIP()).

load

Push a new record with the next number on the front. Usage:

$instance->load(whatever args you want to push);

Or, if the current record isn't associated with the number immediately after the previous record,

$instance->load(LSKIP $n, args);

where $n is the number of lines between this load() call and the last one.

Returns a coderef that you can call to chain loads. For example, this works:

$instance->load(...)->(...)(...)(...) ... ;
# You need an arrow ^^ here, but don't need any after that.

add

Add to the array being built, without inserting the number on the front. Does increment the number and respect skips, for consistency.

Returns the instance.

FUNCTIONS

LSKIP

A convenience function to create a skipper. Prototyped as ($) so you can use it conveniently with load():

$instance->load(LSKIP 1, whatever args...);

If you are using line numbers, the parameter to LSKIP should be the number of lines above the current line and below the last new() or load() call. For example:

my $instance = List::AutoNumbered->new(__LINE__);
# A line
# Another one
$instance->load(LSKIP 2,    # two comment lines between new() and here
                'some data');

INTERNAL PACKAGES

List::AutoNumbered::Skipper

This package represents a skip and is created by LSKIP(). No user-serviceable parts inside.

new

Creates a new skipper. Parameters are for internal use only and are not part of the public API.

GLOBALS

$TRACE

(Default falsy) If truthy, print trace output. Must be accessed directly unless requested on the use line. Either of the following works:

use List::AutoNumbered; $List::AutoNumbered::TRACE=1;
use List::AutoNumbered q(*TRACE); $TRACE=1;

AUTHOR

Christopher White, <cxwembedded at gmail.com>

BUGS

Please report any bugs or feature requests through the web interface at https://github.com/cxw42/List-AutoNumbered/issues. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc List::AutoNumbered

You can also look for information at:

• MetaCPAN

  https://metacpan.org/pod/List::AutoNumbered

• Appveyor (CI builds)

  https://ci.appveyor.com/project/cxw42/list-autonumbered

ACKNOWLEDGEMENTS

Thanks to zdim for discussion and ideas in the Stack Overflow question that was the starting point for this module.

Thanks to Dan Stewart for code contributions.

LICENSE AND COPYRIGHT

Copyright 2019--2020 Christopher White.

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See http://dev.perl.org/licenses/ for more information.

list-autonumbered's Issues

Support user-provided list-entry-making function

Currently, each item of the list is [<number>, <other stuff the user provides>]. Instead, permit the user to specify a function that takes the <number> and the <stuff>, and returns one or more items to push to the list.

Add override to return @{self->arr} in list context

Using overload, overload the @{} operation so that using an instance as an array returns the contents of $self->arr (arr). This will permit:

my $list = List::AutoNumbered->new...;
foreach my $item ($list) { ... }    # Instead of my $item (@{$list->arr})