NAME
Comparer - Reusable comparer subroutines
SPECIFICATION VERSION
0.1
VERSION
This document describes version 0.1.1 of Comparer (from Perl distribution Comparer), released on 2024-01-23.
SYNOPSIS
Basic:
use Comparer::naturally;
my $cmp = Comparer::naturally::gen_comparer;
my @sorted = sort { $cmp->($a,$b) } ('track1.mp3', 'track10.mp3', 'track2.mp3', 'track1b.mp3', 'track1a.mp3');
# => ('track1.mp3', 'track1a.mp3', 'track1b.mp3', 'track2.mp3', 'track10.mp3')
Specifying arguments:
use Comparer::naturally;
my $cmp = Comparer::naturally::gen_comparer(reverse => 1);
my @sorted = sort { $cmp->($a,$b) } ...;
Specifying comparer on the command-line (for other CLI's):
% customsort -c naturally ...
% customsort -c naturally=reverse,1 ...
DESCRIPTION
EXPERIMENTAL. SPEC MIGHT STILL CHANGE.
Glossary
A comparer is a subroutine that accepts two items to be compare and return a value of either -1/0/1. So in other words, just like Perl's cmp
or <=>
.
A comparer module is a module under the Comparer::*
namespace that you can use to generate a comparer.
Writing a Comparer module
package Comparer::naturally;
# required. must return a hash (DefHash)
sub meta {
return +{
v => 1,
args => {
reverse => {
schema => 'bool*', # Sah schema
},
},
};
}
sub gen_comparer {
my %args = @_;
...
}
1;
Namespace organization
HOMEPAGE
Please visit the project's homepage at https://metacpan.org/release/Comparer.
SOURCE
Source repository is at https://github.com/perlancar/perl-Comparer.
SEE ALSO
Base specifications
Related specifications
Previous incarnation
Sorter
, SortKey
, and Comparer
are meant to eventually supersede Sort::Sub. The main improvement over Sort::Sub is the split into three kinds of subroutines:
- 1. sorter
-
A subroutine that accepts a list of items to sort.
Sorter::*
modules are meant to generate sorters. - 2. sort key generator
-
A subroutine that converts an item to a string/numeric key suitable for simple comparison using
eq
or==
during sorting.SortKey::*
modules are meant to generate sort key generators. - 3. comparer
-
A subroutine that compares two items. Can be used in
sort()
as custom sort block.Comparer::*
modules are meant to generate comparers.Perl's
sort()
, as mentioned above, allows us to specify a comparer, but oftentimes it's more efficient to sort by key using key generator, where the keys are often cached. And sometimes due to preprocessing and/or postprocessing it's more suitable to use the more generic sorter interface.
Aside from the above, Comparer
also makes Sort::Sub's special arguments reverse
and is_ci
become ordinary arguments, because they are not always applicable in all situation, especially is_ci
.
AUTHOR
perlancar <perlancar@cpan.org>
CONTRIBUTING
To contribute, you can send patches by email/via RT, or send pull requests on GitHub.
Most of the time, you don't need to build the distribution yourself. You can simply modify the code, then test via:
% prove -l
If you want to build the distribution (e.g. to try to install it locally on your system), you can install Dist::Zilla, Dist::Zilla::PluginBundle::Author::PERLANCAR, Pod::Weaver::PluginBundle::Author::PERLANCAR, and sometimes one or two other Dist::Zilla- and/or Pod::Weaver plugins. Any additional steps required beyond that are considered a bug and can be reported to me.
COPYRIGHT AND LICENSE
This software is copyright (c) 2024 by perlancar <perlancar@cpan.org>.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.
BUGS
Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=Comparer
When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.