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Perl::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 Regex::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.

AUTHOR

Jeffrey Ryan Thalhammer <thaljef@cpan.org>

COPYRIGHT

Copyright (c) 2005-2008 Jeffrey Ryan Thalhammer. 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.