Perl::CrPerl::Critic::Policy::RegularExpressions::RequireExtendedFormatting(3)NAMEPerl::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.Perl::Critic::Policy::RegularExpressions::RequireExtendedFormatting(3)
