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.IX Title "Perl::Critic::Policy::RegularExpressions::RequireExtendedFormatting 3pm"
.TH Perl::Critic::Policy::RegularExpressions::RequireExtendedFormatting 3pm 2023-07-26 "perl v5.38.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH NAME
Perl::Critic::Policy::RegularExpressions::RequireExtendedFormatting \- Always use the "/x" modifier with regular expressions.
.SH AFFILIATION
.IX Header "AFFILIATION"
This Policy is part of the core Perl::Critic
distribution.
.SH DESCRIPTION
.IX Header "DESCRIPTION"
Extended regular expression formatting allows you mix whitespace and
comments into the pattern, thus making them much more readable.
.PP
.Vb 1
\&    # Match a single\-quoted string efficiently...
\&
\&    m{\*(Aq[^\e\e\*(Aq]*(?:\e\e.[^\e\e\*(Aq]*)*\*(Aq};  #Huh?
\&
\&    # Same thing with extended format...
\&
\&    m{
\&        \*(Aq           # an opening single quote
\&        [^\e\e\*(Aq]      # any non\-special chars (i.e. not backslash or single quote)
\&        (?:         # then all of...
\&            \e\e .    #    any explicitly backslashed char
\&            [^\e\e\*(Aq]* #    followed by a non\-special char
\&        )*          # ...repeated zero or more times
\&        \*(Aq           # a closing single quote
\&    }x;
.Ve
.SH CONFIGURATION
.IX Header "CONFIGURATION"
You might find that putting a \f(CW\*(C`/x\*(C'\fR on short regular expressions to be
excessive.  An exception can be made for them by setting
\&\f(CW\*(C`minimum_regex_length_to_complain_about\*(C'\fR to the minimum match length
you'll allow without a \f(CW\*(C`/x\*(C'\fR.  The length only counts the regular
expression, not the braces or operators.
.PP
.Vb 2
\&    [RegularExpressions::RequireExtendedFormatting]
\&    minimum_regex_length_to_complain_about = 5
\&
\&    $num =~ m<(\ed+)>;              # ok, only 5 characters
\&    $num =~ m<\ed\e.(\ed+)>;          # not ok, 9 characters
.Ve
.PP
This option defaults to 0.
.PP
Because using \f(CW\*(C`/x\*(C'\fR 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 \f(CW\*(C`strict\*(C'\fR option.
.PP
.Vb 2
\&    [RegularExpressions::RequireExtendedFormatting]
\&    strict = 1
\&
\&    $string =~ m/Basset hounds got long ears/;  # no longer ok
.Ve
.PP
This option defaults to false.
.SH NOTES
.IX Header "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.
.SH "TO DO"
.IX Header "TO DO"
Add an exemption for regular expressions that contain \f(CW\*(C`\eQ\*(C'\fR at the
front and don't use \f(CW\*(C`\eE\*(C'\fR until the very end, if at all.
.SH AUTHOR
.IX Header "AUTHOR"
Jeffrey Ryan Thalhammer  <jeff@imaginative\-software.com>
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright (c) 2005\-2011 Imaginative Software Systems. All rights reserved.
.PP
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.