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perl::critic::policy::regularexpressions::prohibitunusedcapture(3pm) [debian man page]

Perl::Critic::Policy::RegularExpressions::ProhibitUnusedUseruContributed Perl Perl::Critic::Policy::RegularExpressions::ProhibitUnusedCapture(3pm)

NAME

       Perl::Critic::Policy::RegularExpressions::ProhibitUnusedCapture - Only use a capturing group if you plan to use the captured value.

AFFILIATION

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

DESCRIPTION

       Perl regular expressions have multiple types of grouping syntax.  The basic parentheses (e.g. "m/(foo)/") captures into the magic variable
       $1.  Non-capturing groups (e.g. "m/(?:foo)/" are useful because they have better runtime performance and do not copy strings to the magic
       global capture variables.

       It's also easier on the maintenance programmer if you consistently use capturing vs. non-capturing groups, because that programmer can tell
       more easily which regexps can be refactored without breaking surrounding code which may use the captured values.

CONFIGURATION

       This Policy is not configurable except for the standard options.

CAVEATS

   "qr//" interpolation
       This policy can be confused by interpolation of "qr//" elements, but those are always false negatives.  For example:

	   my $foo_re = qr/(foo)/;
	   my ($foo) = m/$foo_re (bar)/x;

       A human can tell that this should be a violation because there are two captures but only the first capture is used, not the second.  The
       policy only notices that there is one capture in the regexp and remains happy.

   "@-", "@+", $LAST_MATCH_START and $LAST_MATCH_END
       This policy will only recognize capture groups referred to by these variables if the use is subscripted by a literal integer.

   $^N and $LAST_SUBMATCH_RESULT
       This policy will not recognize capture groups referred to only by these variables, because there is in general no way by static analysis to
       determine which capture group is referred to.  For example,

	   m/ (?: (A[[:alpha:]]+) | (Nd+) ) (?{$foo=$^N}) /smx

       makes use of the first capture group if it matches, or the second capture group if the first does not match but the second does.

CREDITS

       Initial development of this policy was supported by a grant from the Perl Foundation.

AUTHOR

       Chris Dolan <cdolan@cpan.org>

COPYRIGHT

       Copyright (c) 2007-2011 Chris Dolan.  Many 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 v5.14.2							    2012-06-07Perl::Critic::Policy::RegularExpressions::ProhibitUnusedCapture(3pm)

Check Out this Related Man Page

Perl::Critic::Policy::RegularExpressions::ProhibitCapturUserhContributed)Perl::Critic::Policy::RegularExpressions::ProhibitCaptureWithoutTest(3pm)

NAME

       Perl::Critic::Policy::RegularExpressions::ProhibitCaptureWithoutTest - Capture variable used outside conditional.

AFFILIATION

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

DESCRIPTION

       If a regexp match fails, then any capture variables ($1, $2, ...) will be undefined.  Therefore it's important to check the return value of
       a match before using those variables.

       This policy checks that the previous regexp for which the capture variable is in-scope is either in a conditional or causes an exception or
       other control transfer (i.e. "next", "last", "redo", "return", or sometimes "goto") if the match fails.

       A "goto" is only accepted by this policy if it is a co-routine call (i.e.  "goto &foo") or a "goto LABEL" where the label does not fall
       between the "goto" and the capture variable in the scope of the "goto". A computed "goto" (i.e. something like "goto (qw{foo bar
       baz})[$i]") is not accepted by this policy because its target can not be statically determined.

       This policy does not check whether that conditional is actually testing a regexp result, nor does it check whether a regexp actually has a
       capture in it.  Those checks are too hard.

       This policy also does not check arbitrarily complex conditionals guarding regexp results, for pretty much the same reason.  Simple things
       like

	m/(foo)/ or die "No foo!";
	die "No foo!" unless m/(foo)/;

       will be handled, but something like

	m/(foo) or do {
	  ... lots of complicated calculations here ...
	  die "No foo!";
	};

       are beyond its scope.

CONFIGURATION

       By default, this policy considers "die", "croak", and "confess" to throw exceptions. If you have additional subroutines or methods that may
       be used in lieu of one of these, you can configure them in your perlcriticrc as follows:

	[RegularExpressions::ProhibitCaptureWithoutTest]
	exception_source = my_exception_generator

BUGS

       This policy does not recognize named capture variables. Yet.

AUTHOR

       Chris Dolan <cdolan@cpan.org>

COPYRIGHT

       Copyright (c) 2006-2011 Chris Dolan.

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

perl v5.14.2							    2012-Perl::Critic::Policy::RegularExpressions::ProhibitCaptureWithoutTest(3pm)
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