perl::critic::policy::regularexpressions::requireextendedformatt(3pm) [debian man page]
Perl::Critic::Policy::RegularExpressions::RequireExtendeUsermContributed PPerl::Critic::Policy::RegularExpressions::RequireExtendedFormatting(3pm) NAME
Perl::Critic::Policy::RegularExpressions::RequireExtendedFormatting - Always use the "/x" modifier with regular expressions. AFFILIATION
This Policy is part of the core Perl::Critic distribution. DESCRIPTION
Extended regular expression formatting allows you mix whitespace and comments into the pattern, thus making them much more readable. # Match a single-quoted string efficiently... m{'[^\']*(?:\.[^\']*)*'}; #Huh? # Same thing with extended format... m{ ' # an opening single quote [^\'] # any non-special chars (i.e. not backslash or single quote) (?: # then all of... \ . # any explicitly backslashed char [^\']* # followed by an non-special chars )* # ...repeated zero or more times ' # a closing single quote }x; CONFIGURATION
You might find that putting a "/x" on short regular expressions to be excessive. An exception can be made for them by setting "minimum_regex_length_to_complain_about" to the minimum match length you'll allow without a "/x". The length only counts the regular expression, not the braces or operators. [RegularExpressions::RequireExtendedFormatting] minimum_regex_length_to_complain_about = 5 $num =~ m<(d+)>; # ok, only 5 characters $num =~ m<d.(d+)>; # not ok, 9 characters This option defaults to 0. Because using "/x" on a regex which has whitespace in it can make it harder to read (you have to escape all that innocent whitespace), by default, you can have a regular expression that only contains whitespace and word characters without the modifier. If you want to restrict this, turn on the "strict" option. [RegularExpressions::RequireExtendedFormatting] strict = 1 $string =~ m/Basset hounds got long ears/; # no longer ok This option defaults to false. NOTES
For common regular expressions like e-mail addresses, phone numbers, dates, etc., have a look at the Regexp::Common module. Also, be cautions about slapping modifier flags onto existing regular expressions, as they can drastically alter their meaning. See <http://www.perlmonks.org/?node_id=484238> for an interesting discussion on the effects of blindly modifying regular expression flags. TO DO
Add an exemption for regular expressions that contain "Q" at the front and don't use "E" until the very end, if at all. AUTHOR
Jeffrey Ryan Thalhammer <jeff@imaginative-software.com> COPYRIGHT
Copyright (c) 2005-2011 Imaginative Software Systems. All 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 2012-0Perl::Critic::Policy::RegularExpressions::RequireExtendedFormatting(3pm)
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Perl::Critic::Policy::RegularExpressions::ProhibitEscapeUseraContributedPerl::Critic::Policy::RegularExpressions::ProhibitEscapedMetacharacters(3) NAME
Perl::Critic::Policy::RegularExpressions::ProhibitEscapedMetacharacters - Use character classes for literal meta-characters instead of escapes. AFFILIATION
This Policy is part of the core Perl::Critic distribution. DESCRIPTION
Ever heard of leaning toothpick syndrome? That comes from writing regular expressions that match on characters that are significant in regular expressions. For example, the expression to match four forward slashes looks like: m//////; Well, this policy doesn't solve that problem (write it as "m{////}" instead!) but solves a related one. As seen above, the escapes make the expression hard to parse visually. One solution is to use character classes. You see, inside of character classes, the only characters that are special are "", "]", "^" and "-", so you don't need to escape the others. So instead of the following loose IPv4 address matcher: m/ d+ . d+ . d+ . d+ /x; You could write: m/ d+ [.] d+ [.] d+ [.] d+ /x; which is certainly more readable, if less recognizable prior the publication of Perl Best Practices. (Of course, you should really use Regexp::Common::net to match IPv4 addresses!) Specifically, this policy forbids backslashes immediately prior to the following characters: { } ( ) . * + ? | # We make special exception for "$" because "/[$]/" turns into "/[5.008006/" for Perl 5.8.6. We also make an exception for "^" because it has special meaning (negation) in a character class. Finally, "[" and "]" are exempt, of course, because they are awkward to represent in character classes. Note that this policy does not forbid unnecessary escaping. So go ahead and (pointlessly) escape "!" characters. CONFIGURATION
This Policy is not configurable except for the standard options. BUGS
Perl treats "m/[#]/x" in unexpected ways. I think it's a bug in Perl itself, but am not 100% sure that I have not simply misunderstood... This part makes sense: "#f" =~ m/[#]f/x; # match "#f" =~ m/[#]a/x; # no match This doesn't: $qr = qr/f/; "#f" =~ m/[#]$qr/x; # no match Neither does this: print qr/[#]$qr/x; # yields '(?x-ism:[#]$qr )' 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 v5.16.3 2014Perl::Critic::Policy::RegularExpressions::ProhibitEscapedMetacharacters(3)