Perl::Critic::Policy::RegularExpressions::ProhibitFixedStringMatches(3)
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 v5Perl::Critic::Policy::RegularExpressions::ProhibitFixedStringMatches(3)
perl-critic 1.134.0 - Generated Tue Jun 4 14:14:19 CDT 2019