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Manual Reference Pages  -  PERL::CRITIC::POLICY::VARIABLES::REQUIRELOCALIZEDPUNCTUATIONVARS (3)

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NAME

Perl::Critic::Policy::Variables::RequireLocalizedPunctuationVars - Magic variables should be assigned as "local".

CONTENTS

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.

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perl v5.20.3 PERL::CRITIC::POLICY::VARIABLES::REQUIRELOCALIZEDPUNCTUATIONVARS (3) 2016-04-03

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