Perl::Critic::Policy::InputOutput::ProhibitBarewordFileHandles - Write C<open my $fh, q{<}, $filename;> instead of C<open FH, q{<}, $filename;>.

Perl-Critic documentation Contained in the Perl-Critic distribution.

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NAME

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Perl::Critic::Policy::InputOutput::ProhibitBarewordFileHandles - Write open my $fh, q{<}, $filename; instead of open FH, q{<}, $filename;.

AFFILIATION

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

DESCRIPTION

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Using bareword symbols to refer to file handles is particularly evil because they are global, and you have no idea if that symbol already points to some other file handle. You can mitigate some of that risk by localizing the symbol first, but that's pretty ugly. Since Perl 5.6, you can use an undefined scalar variable as a lexical reference to an anonymous filehandle. Alternatively, see the IO::Handle or IO::File or FileHandle modules for an object-oriented approach.

    open FH, '<', $some_file;           #not ok
    open my $fh, '<', $some_file;       #ok
    my $fh = IO::File->new($some_file); #ok

There are three exceptions: STDIN, STDOUT and STDERR. These three standard filehandles are always package variables.

CONFIGURATION

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This Policy is not configurable except for the standard options.

SEE ALSO

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IO::Handle

IO::File

AUTHOR

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Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>

COPYRIGHT

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Copyright (c) 2005-2011 Imaginative Software Systems. All rights reserved.

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

Perl-Critic documentation Contained in the Perl-Critic distribution. 
##############################################################################
#      $URL: http://perlcritic.tigris.org/svn/perlcritic/trunk/distributions/Perl-Critic/lib/Perl/Critic/Policy/InputOutput/ProhibitBarewordFileHandles.pm $
#     $Date: 2011-05-15 16:34:46 -0500 (Sun, 15 May 2011) $
#   $Author: clonezone $
# $Revision: 4078 $
##############################################################################

package Perl::Critic::Policy::InputOutput::ProhibitBarewordFileHandles;

use 5.006001;
use strict;
use warnings;
use Readonly;

use Perl::Critic::Utils qw{ :severities :classification :ppi };
use base 'Perl::Critic::Policy';

our $VERSION = '1.116';

#-----------------------------------------------------------------------------

Readonly::Scalar my $DESC => q{Bareword file handle opened};
Readonly::Scalar my $EXPL => [ 202, 204 ];

#-----------------------------------------------------------------------------

sub supported_parameters { return ()                  }
sub default_severity     { return $SEVERITY_HIGHEST   }
sub default_themes       { return qw( core pbp bugs ) }
sub applies_to           { return 'PPI::Token::Word'  }

#-----------------------------------------------------------------------------

sub violates {
    my ($self, $elem, undef) = @_;

    return if $elem ne 'open';
    return if ! is_function_call($elem);

    my $first_arg = ( parse_arg_list($elem) )[0];
    return if !$first_arg;
    my $first_token = $first_arg->[0];
    return if !$first_token;

    if ( $first_token->isa('PPI::Token::Word') ) {
        if ( ($first_token ne 'my') && ($first_token !~ m/^STD(?:IN|OUT|ERR)$/xms ) ) {
            return $self->violation( $DESC, $EXPL, $elem );
        }
    }
    return; #ok!
}

1;

__END__

#-----------------------------------------------------------------------------


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