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.