/ 
Perl-Critic-Policy-RegularExpressions-ProhibitRegexForStringEquality-0.001
/ Perl::Critic::Policy::RegularExpressions::ProhibitRegexForStringEquality

NAME

Perl::Critic::Policy::RegularExpressions::ProhibitRegexForStringEquality - Compare a string with eq, not with a regex anchored at both ends.

VERSION

version 0.001

Perl::Critic::Policy::RegularExpressions::ProhibitRegexForStringEquality

A match of literal text anchored at both ends asks whether a string is that text, which is eq. An anchored group of literal alternatives asks whether a string is one of several, which is any from List::Util, or a hash lookup. Either one says what it does in plain words, and runs no pattern:

if ( $name =~ m/\Afoo\z/ ) { ... }                   # reported
if ( $name eq 'foo' ) { ... }

return if $tool =~ m/\A(?:Skill|Read)\z/;           # reported
return if List::Util::any { $tool eq $_ } qw{Skill Read};

PROHIBITED

$str =~ m/\Afoo\z/          # eq
$str !~ m/\Afoo\z/          # ne
$str =~ m/^foo\z/           # ^ is the start without /m
$str =~ m/\Afoo\.bar\z/     # an escaped character is still literal text
$str =~ m/\A foo \z/x       # under /x this is the string foo
$str =~ m/\A(?:foo)\z/      # a group of one alternative is still eq
$str =~ m/\A(?:a|b|c)\z/    # any, or a hash lookup
$str !~ m/\A(?:a|b)\z/      # none, or a failed hash lookup
grep { m/\Afoo\z/ } @names  # a match against $_ counts too

ALLOWED

$str =~ m/\Afoo$/           # $ also matches before a trailing newline
$str =~ m/\Afoo\Z/          # so does \Z
$str =~ m/^foo\z/m          # /m: ^ is the start of any line
$str =~ m/\Afoo\z/i         # /i, which eq cannot do
$str =~ m/\A(foo|bar)\z/    # a capture, which the code may use
$str =~ m/\A(?i:a|b)\z/     # a group with modifiers of its own
$str =~ m/\Afoo|bar\z/      # alternation outside a group anchors each side once
$str =~ m/\Afo+\z/          # a quantifier
$str =~ m/\A[ab]\z/         # a character class
$str =~ m/\A$foo\z/         # interpolation
$str =~ m/\A\z/             # nothing between the anchors, see CAVEATS
$str =~ s/\Afoo\z/bar/      # a substitution
my $rx = qr/\Afoo\z/;       # a compiled regex
split m/\Afoo\z/, $str;     # the pattern that split takes

MODIFIERS

/i exempts a pattern, because eq is case sensitive. fc on both sides would do, but that is a rewrite and not a substitution.

/m exempts a pattern that starts with ^, because ^ then matches at the start of any line. A pattern that starts with \A is reported under /m too.

/g exempts a pattern, because in scalar context it moves pos, which eq does not.

/s and /x change nothing here: there is no . in literal text, and whitespace under /x is not text.

A modifier in scope from a use re counts the same as one written on the match, so a file under use re '/i' is exempt throughout.

CAVEATS

m/\A\z/ is eq q{}, or !length, but it is not reported. The policy asks for text between the anchors.

A group of one alternative is reported as eq, and a group of more than one as any. Where the alternatives are many, or the test runs in a loop, a hash of them built once is faster than any.

METHODS

supported_parameters

default_severity

default_themes

applies_to

violates

Standard Perl::Critic::Policy interface. Returns a violation for a match whose pattern is literal text, or a plain group of literal alternatives, between a start anchor and \z.

BUGS

Please report any bugs or feature requests on the bugtracker website https://github.com/teodesian/perl-critic-policy-prohibitregexforstringequality/issues

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.

AUTHORS

Current Maintainers:

  • George S. Baugh <george@troglodyne.net>

COPYRIGHT AND LICENSE

Copyright (c) 2026 Troglodyne LLC

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.