ELLIOTJS / Perl-Critic-1.083_004 / lib / Perl / Critic / Policy / InputOutput / ProhibitReadlineInForLoop.pm 

            

              
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##############################################################################
#      $URL: http://perlcritic.tigris.org/svn/perlcritic/trunk/Perl-Critic/lib/Perl/Critic/Policy/InputOutput/ProhibitReadlineInForLoop.pm $
#     $Date: 2008-05-18 18:49:57 -0500 (Sun, 18 May 2008) $
#   $Author: clonezone $
# $Revision: 2367 $
##############################################################################
package Perl::Critic::Policy::InputOutput::ProhibitReadlineInForLoop;
use strict;
use warnings;
use Readonly;
use Perl::Critic::Utils qw{ :severities };
use base 'Perl::Critic::Policy';
our $VERSION = '1.083_004';
#-----------------------------------------------------------------------------
Readonly::Scalar my $DESC => q{Readline inside "for" loop};
Readonly::Scalar my $EXPL => [ 211 ];
#-----------------------------------------------------------------------------
sub supported_parameters { return ()                           }
sub default_severity     { return $SEVERITY_HIGH               }
sub default_themes       { return qw( core bugs pbp )          }
sub applies_to           { return qw( PPI::Structure::ForLoop) }
#-----------------------------------------------------------------------------
sub violates {
    my ( $self, $elem, undef ) = @_;
    if ( my $rl = $elem->find_first('PPI::Token::QuoteLike::Readline') ) {
        return $self->violation( $DESC, $EXPL, $rl );
    }
    return;  #ok!
}
1;
__END__
#-----------------------------------------------------------------------------
=pod
=head1 NAME
Perl::Critic::Policy::InputOutput::ProhibitReadlineInForLoop - Write C<< while( $line = <> ){...} >> instead of C<< for(<>){...} >>.
=head1 AFFILIATION
This Policy is part of the core L<Perl::Critic> distribution.
=head1 DESCRIPTION
Using the readline operator in a C<for> or C<foreach> loop is very
slow.  The iteration list of the loop creates a list context,
which causes the readline operator to read the entire input stream
before iteration even starts.  Instead, just use a C<while> loop,
which only reads one line at a time.
  for my $line ( <$file_handle> ){ do_something($line) }      #not ok
  while ( my $line = <$file_handle> ){ do_something($line) }  #ok
=head1 CONFIGURATION
This Policy is not configurable except for the standard options.
=head1 AUTHOR
Jeffrey Ryan Thalhammer <thaljef@cpan.org>
=head1 COPYRIGHT
Copyright (c) 2005-2008 Jeffrey Ryan Thalhammer.  All 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.
=cut
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