English(3pm) Perl Programmers Reference Guide English(3pm)NAME
English - use nice English (or awk) names for ugly punctuation variables
SYNOPSIS
use English;
use English qw( -no_match_vars ) ; # Avoids regex performance penalty
# in perl 5.16 and earlier
...
if ($ERRNO =~ /denied/) { ... }
DESCRIPTION
This module provides aliases for the built-in variables whose names no one seems to like to read. Variables with side-effects which get
triggered just by accessing them (like $0) will still be affected.
For those variables that have an awk version, both long and short English alternatives are provided. For example, the $/ variable can be
referred to either $RS or $INPUT_RECORD_SEPARATOR if you are using the English module.
See perlvar for a complete list of these.
PERFORMANCE
NOTE: This was fixed in perl 5.20. Mentioning these three variables no longer makes a speed difference. This section still applies if
your code is to run on perl 5.18 or earlier.
This module can provoke sizeable inefficiencies for regular expressions, due to unfortunate implementation details. If performance matters
in your application and you don't need $PREMATCH, $MATCH, or $POSTMATCH, try doing
use English qw( -no_match_vars ) ;
. It is especially important to do this in modules to avoid penalizing all applications which use them.
perl v5.18.2 2014-01-06 English(3pm)
Check Out this Related Man Page
Perl::Critic::Policy::Variables::ProhibitMatchVars(3pm) User Contributed Perl DocumentationPerl::Critic::Policy::Variables::ProhibitMatchVars(3pm)NAME
Perl::Critic::Policy::Variables::ProhibitMatchVars - Avoid "$`", "$&", "$'" and their English equivalents.
AFFILIATION
This Policy is part of the core Perl::Critic distribution.
DESCRIPTION
Using the "match variables" "$`", $&, and/or "$'" can significantly degrade the performance of a program. This policy forbids using them
or their English equivalents. See perldoc English or PBP page 82 for more information.
It used to forbid plain "use English;" because it ends up causing the performance side-effects of the match variables. However, the
message emitted for that situation was not at all clear and there is now Perl::Critic::Policy::Modules::RequireNoMatchVarsWithUseEnglish,
which addresses this situation directly.
CONFIGURATION
This Policy is not configurable except for the standard options.
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. The full text of this license
can be found in the LICENSE file included with this module.
perl v5.14.2 2012-06-07 Perl::Critic::Policy::Variables::ProhibitMatchVars(3pm)
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