NAME

       Perl::Critic::Policy::RegularExpressions::ProhibitFixedStringMatches - Use "eq" or hash
       instead of fixed-pattern regexps.

AFFILIATION

       This Policy is part of the core Perl::Critic distribution.

DESCRIPTION

       A regular expression that matches just a fixed set of constant strings is wasteful of
       performance and is hard on maintainers.  It is much more readable and often faster to use
       "eq" or a hash to match such strings.

           # Bad
           my $is_file_function = $token =~ m/\A (?: open | close | read ) \z/xms;

           # Faster and more readable
           my $is_file_function = $token eq 'open' ||
                                  $token eq 'close' ||
                                  $token eq 'read';

       For larger numbers of strings, a hash is superior:

           # Bad
           my $is_perl_keyword =
               $token =~ m/\A (?: chomp | chop | chr | crypt | hex | index
                                  lc | lcfirst | length | oct | ord | ... ) \z/xms;

           # Better
           Readonly::Hash my %PERL_KEYWORDS => map {$_ => 1} qw(
               chomp chop chr crypt hex index lc lcfirst length oct ord ...
           );
           my $is_perl_keyword = $PERL_KEYWORD{$token};

       Conway also suggests using "lc()" instead of a case-insensitive match.

   VARIANTS
       This policy detects both grouped and non-grouped strings.  The grouping may or may not be
       capturing.  The grouped body may or may not be alternating.  "\A" and "\z" are always
       considered anchoring which "^" and "$" are considered anchoring is the "m" regexp option
       is not in use.  Thus, all of these are violations:

           m/^foo$/;
           m/\A foo \z/x;
           m/\A foo \z/xm;
           m/\A(foo)\z/;
           m/\A(?:foo)\z/;
           m/\A(foo|bar)\z/;
           m/\A(?:foo|bar)\z/;

       Furthermore, this policy detects violations in "m//", "s///" and "qr//" constructs, as you
       would expect.

CONFIGURATION

       This Policy is not configurable except for the standard options.

CREDITS

       Initial development of this policy was supported by a grant from the Perl Foundation.

AUTHOR

       Chris Dolan <cdolan@cpan.org>

COPYRIGHT

       Copyright (c) 2007-2011 Chris Dolan.  Many rights reserved.

       This program is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.  The full text of this license can be found in the LICENSE file
       included with this module

perl v5.20.2            Perl::Critic::Policy::RegularExpressions::ProhibitFixedStringMatches(3pm)