Perl::Critic::Policy::RegularExpressions::RequireLineBoundaryMatching - Always use the /m modifier with regular expressions.


This Policy is part of the core Perl::Critic distribution.


Folks coming from a sed or awk background tend to assume that '$' and '^' match the beginning and end of the line, rather than then beginning and end of the string. Adding the '/m' flag to your regex makes it behave as most people expect it should.

    my $match = m{ ^ $pattern $ }x;  #not ok
    my $match = m{ ^ $pattern $ }xm; #ok


This Policy is not configurable except for the standard options.


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 for an interesting discussion on the effects of blindly modifying regular expression flags.


Jeffrey Ryan Thalhammer <>


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.