Perl::Critic::Policy::RegularExpressions::ProhibitFixedSUsergContributed)Perl::Critic::Policy::RegularExpressions::ProhibitFixedStringMatches(3pm)

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 v5.14.2							    2012-Perl::Critic::Policy::RegularExpressions::ProhibitFixedStringMatches(3pm)