NAME¶
Perl::Critic::Policy::Variables::RequireLocalizedPunctuationVars - Magic
variables should be assigned as "local".
AFFILIATION¶
This Policy is part of the core Perl::Critic distribution.
DESCRIPTION¶
Punctuation variables (and their English.pm equivalents) are global variables.
Messing with globals is dangerous in a complex program as it can lead to very
subtle and hard to fix bugs. If you must change a magic variable in a
non-trivial program, do it in a local scope.
For example, to slurp a filehandle into a scalar, it's common to set the record
separator to undef instead of a newline. If you choose to do this (instead of
using File::Slurp!) then be sure to localize the global and change it for as
short a time as possible.
# BAD:
$/ = undef;
my $content = <$fh>;
# BETTER:
my $content;
{
local $/ = undef;
$content = <$fh>;
}
# A popular idiom:
my $content = do { local $/ = undef; <$fh> };
This policy also allows the use of "my". Perl prevents using
"my" with "proper" punctuation variables, but allows $a,
@ARGV, the names declared by English, etc. This is not a good coding practice,
however it is not the concern of this specific policy to complain about that.
There are exemptions for $_ and @_, and the English equivalent $ARG.
CONFIGURATION¶
You can configure your own exemptions using the "allow" option:
[Variables::RequireLocalizedPunctuationVars]
allow = @ARGV $ARGV
These are added to the default exemptions.
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.