Provided by: libregexp-pattern-perl_0.2.8-2_all bug


       Regexp::Pattern - Convention/framework for modules that contain collection of regexes




       This document describes version 0.2.8 of Regexp::Pattern (from Perl distribution Regexp-
       Pattern), released on 2018-09-12.


       Subroutine interface:

        use Regexp::Pattern; # exports re()

        my $re = re('YouTube::video_id');
        say "ID does not look like a YouTube video ID" unless $id =~ /\A$re\z/;

        # a dynamic pattern (generated on-demand) with generator arguments
        my $re2 = re('Example::re3', {variant=>"B"});

       Hash interface (a la Regexp::Common but simpler with regular/non-magical hash that is only
       1-level deep):

        use Regexp::Pattern 'YouTube::video_id';
        say "ID does not look like a YouTube video ID"
            unless $id =~ /\A$RE{video_id}\z/;

        # more complex example

        use Regexp::Pattern (
            're',                                # we still want the re() function
            'Foo::bar' => (-as => 'qux'),        # the pattern will be in your $RE{qux}
            'YouTube::*',                        # wildcard import
            'Example::re3' => (variant => 'B'),  # supply generator arguments
            'JSON::*' => (-prefix => 'json_'),   # add prefix
            'License::*' => (
              -has_tag    => 'family:cc',        # select by tag
              -lacks_tag  => 'type:unversioned', #   also select by lack of tag
              -suffix     => '_license',         #   also add suffix


       Regexp::Pattern is a convention for organizing reusable regexp patterns in modules, as
       well as framework to provide convenience in using those patterns in your program.

   Structure of an example Regexp::Pattern::* module
        package Regexp::Pattern::Example;

        our %RE = (
            # the minimum spec
            re1 => { pat => qr/\d{3}-\d{3}/ },

            # more complete spec
            re2 => {
                summary => 'This is regexp for blah',
                description => <<'_',

        A longer description.

                pat => qr/\d{3}-\d{3}(?:-\d{5})?/,
                tags => ['A','B'],
                examples => [
                        str => '123-456',
                        matches => 1,
                        summary => 'Another example that matches',
                        str => '123-456-78901',
                        matches => 1,
                        summary => 'An example that does not match',
                        str => '123456',
                        matches => 0,
                        summary => 'An example that does not get tested',
                        str => '123456',
                        summary => 'Another example that does not get tested nor rendered to POD',
                        str => '234567',
                        matches => 0,
                        test => 0,
                        doc => 0,

            # dynamic (regexp generator)
            re3 => {
                summary => 'This is a regexp for blah blah',
                description => <<'_',


                gen => sub {
                    my %args = @_;
                    my $variant = $args{variant} || 'A';
                    if ($variant eq 'A') {
                        return qr/\d{3}-\d{3}/;
                    } else { # B
                        return qr/\d{3}-\d{2}-\d{5}/;
                gen_args => {
                    variant => {
                        summary => 'Choose variant',
                        schema => ['str*', in=>['A','B']],
                        default => 'A',
                        req => 1,
                tags => ['B','C'],
                examples => [
                        summary => 'An example that matches',
                        gen_args => {variant=>'A'},
                        str => '123-456',
                        matches => 1,
                        summary => "An example that doesn't match",
                        gen_args => {variant=>'B'},
                        str => '123-456',
                        matches => 0,

            re4 => {
                summary => 'This is a regexp that does capturing',
                tags => ['capturing'],
                pat => qr/(\d{3})-(\d{3})/,
                examples => [
                    {str=>'123-456', matches=>[123, 456]},
                    {str=>'foo-bar', matches=>[]},

            re5 => {
                summary => 'This is another regexp that does (named) capturing and anchoring',
                tags => ['capturing', 'anchored'],
                pat => qr/^(?<cap1>\d{3})-(?<cap2>\d{3})/,
                examples => [
                    {str=>'123-456', matches=>{cap1=>123, cap2=>456}},
                    {str=>'something 123-456', matches=>{}},

       A Regexp::Pattern::* module must declare a package global hash variable named %RE. Hash
       keys are pattern names, hash values are pattern definitions in the form of defhashes (see

       Pattern name should be a simple identifier that matches this regexp:
       "/\A[A-Za-z_][A-Za-z_0-9]*\z/". The definition for the qualified pattern name
       "Foo::Bar::baz" can then be located in %Regexp::Pattern::Foo::Bar::RE under the hash key

       Pattern definition hash should at the minimum be:

        { pat => qr/.../ }

       You can add more stuffs from the defhash specification, e.g. summary, description, tags,
       and so on, for example (taken from Regexp::Pattern::CPAN):

            summary     => 'PAUSE author ID, or PAUSE ID for short',
            pat         => qr/[A-Z][A-Z0-9]{1,8}/,
            description => <<~HERE,
            I'm not sure whether PAUSE allows digit for the first letter. For safety
            I'm assuming no.
            examples => [
                {str=>'PERLANCAR', matches=>1},
                {str=>'BAD ID', matches=>0},

       Examples. Your regexp specification can include an "examples" property (see above for
       example). The value of the "examples" property is an array, each of which should be a
       defhash. For each example, at the minimum you should specify "str" (string to be matched
       by the regexp), "gen_args" (hash, arguments to use when generating dynamic regexp
       pattern), and "matches" (a boolean value that specifies whether the regexp should match
       the string or not, or an array/hash that specifies the captures). You can of course
       specify other defhash properties (e.g. "summary", "description", etc). Other example
       properties might be introduced in the future.

       If you use Dist::Zilla to build your distribution, you can use the plugin
       [Regexp::Pattern] to test the examples during building, and the Pod::Weaver plugin
       [-Regexp::Pattern] to render the examples in your POD.

   Using a Regexp::Pattern::* module

       A Regexp::Pattern::* module can be used in a standalone way (i.e. no need to use via the
       Regexp::Pattern framework), as it simply contains data that can be grabbed using a normal
       means, e.g.:

        use Regexp::Pattern::Example;

        say "Input does not match blah"
            unless $input =~ /\A$Regexp::Pattern::Example::RE{re1}{pat}\z/;

       Via Regexp::Pattern, sub interface

       Regexp::Pattern (this module) also provides "re()" function to help retrieve the regexp
       pattern. See "re" for more details.

       Via Regexp::Pattern, hash interface

       Additionally, Regexp::Pattern (since v0.2.0) lets you import regexp patterns into your %RE
       package hash variable, a la Regexp::Common (but simpler because the hash is just a regular
       hash, only 1-level deep, and not magical).

       To import, you specify qualified pattern names as the import arguments:

        use Regexp::Pattern 'Q::pat1', 'Q::pat2', ...;

       Each qualified pattern name can optionally be followed by a list of name-value pairs. A
       pair name can be an option name (which is dash followed by a word, e.g.  "-as", "-prefix")
       or a generator argument name for dynamic pattern.

       Wildcard import. Instead of a qualified pattern name, you can use 'Module::SubModule::*'
       wildcard syntax to import all patterns from a pattern module.

       Importing into a different name. You can add the import option "-as" to import into a
       different name, for example:

        use Regexp::Pattern 'YouTube::video_id' => (-as => 'yt_id');

       Prefix and suffix. You can also add a prefix and/or suffix to the imported name:

        use Regexp::Pattern 'Example::*' => (-prefix => 'example_');
        use Regexp::Pattern 'Example::*' => (-suffix => '_sample');

       Filtering. When wildcard-importing, you can select the patterns you want using a
       combination of these options: "-has_tag" (only select patterns that have a specified tag),
       "-lacks_tag" (only select patterns that do not have a specified tag).

   Recommendations for writing the regex patterns
       ·   Regexp pattern should be written as a "qr//" literal

           Using a string literal is less desirable. That is:

            pat => qr/foo[abc]+/,

           is preferred over:

            pat => 'foo[abc]+',

       ·   Regexp pattern should not be anchored (unless really necessary)

           That is:

            pat => qr/foo/,

           is preferred over:

            pat => qr/^foo/, # or qr/foo$/, or qr/\Afoo\z/

           Adding anchors limits the reusability of the pattern. When composing pattern, user can
           add anchors herself if needed.

           When you define an anchored pattern, adding tag "anchored" is recommended:

            tags => ['anchored'],

       ·   Regexp pattern should not contain capture groups (unless really necessary)

           Adding capture groups limits the reusability of the pattern because it can affect the
           groups of the composed pattern. When composing pattern, user can add captures herself
           if needed.

           When you define an anchored pattern, adding tag "capturing" is recommended:

            tags => ['capturing'],


       Exported by default. Get a regexp pattern by name from a "Regexp::Pattern::*" module.


        re($name[, \%args ]) => $re

       $name is MODULE_NAME::PATTERN_NAME where MODULE_NAME is name of a "Regexp::Pattern::*"
       module without the "Regexp::Pattern::" prefix and PATTERN_NAME is a key to the %RE package
       global hash in the module. A dynamic pattern can accept arguments for its generator, and
       you can pass it as hashref in the second argument of "re()".

       Anchoring. You can also put "-anchor => 1" in %args. This will conveniently wraps the
       regex inside "qr/\A(?:...)\z/".

       Die when pattern by name $name cannot be found (either the module cannot be loaded or the
       pattern with that name is not found in the module).


       Please visit the project's homepage at <>.


       Source repository is at <>.


       Please report any bugs or feature requests on the bugtracker website

       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.


       Regexp::Common. Regexp::Pattern is an alternative to Regexp::Common.  Regexp::Pattern
       offers simplicity and lower startup overhead. Instead of a magic hash, you retrieve
       available regexes from normal data structure or via the provided "re()" function.
       Regexp::Pattern also provides a hash interface, albeit the hash is not magic.

       Regexp::Common::RegexpPattern, a bridge module to use patterns in "Regexp::Pattern::*"
       modules via Regexp::Common.

       Regexp::Pattern::RegexpCommon, a bridge module to use patterns in "Regexp::Common::*"
       modules via Regexp::Pattern.


       If you use Dist::Zilla: Dist::Zilla::Plugin::Regexp::Pattern,

       Test::Regexp::Pattern and test-regexp-pattern.


       perlancar <>


       This software is copyright (c) 2018, 2016 by

       This is free software; you can redistribute it and/or modify it under the same terms as
       the Perl 5 programming language system itself.