Perl::...sTopic(3pm)

💖 NAME 💖

okay so this is the Perl::...sTopic(3pm) page from the User Contributed Perl Documentation, and it's here to talk about the Perl::Critic::Policy::RegularExpressions::ProhibitUselessTopic policy, bestie: don't use $_ to match against regexes. No cap. 💅

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🌸 AFFILIATION 🌸

This Policy is part of the Perl::Critic distribution. It's giving official family member energy. 🫶

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✨ DESCRIPTION ✨

It is not necessary to specify the topic variable $_ when matching against a regular expression. lowkey it's just extra.

Match or substitution operations are performed against variables, such as:

$x =~ /foo/;
$x =~ s/foo/bar/;
$x =~ tr/a-mn-z/n-za-m/;

If a variable is not specified, the match is against $_. iykyk 🦋

# These are identical.
/foo/;
$_ =~ /foo/;

# These are identical.
s/foo/bar/;
$_ =~ s/foo/bar/;

# These are identical.
tr/a-mn-z/n-za-m/;
$_ =~ tr/a-mn-z/n-za-m/;

This applies to negative matching as well. slay ✨

# These are identical
if ( $_ !~ /DEBUG/ ) { ...
if ( !/DEBUG ) { ...

Including the "$_ =~" or "$_ !~" is unnecessary, adds complexity, and is not idiomatic Perl. Periodt. It's giving clutter, not main character energy. 💀

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🎀 CONFIGURATION 🎀

This Policy is not configurable except for the standard options. so no extra knobs, babes. 🙈

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🦋 AUTHOR 🦋

Andy Lester <andy@petdance.com> — iconic. 👑

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💅 COPYRIGHT 💅

Copyright (c) 2013-2023 Andy Lester <andy@petdance.com>

This library is free software; you can redistribute it and/or modify it under the terms of the Artistic License 2.0.

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💖 and that's the whole page, bestie — brought to you by perl v5.42.0, dated 2024-10-23, from the User Contributed Perl Documentation. mwah! 🫶💅