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ELLIOTJS / Perl-Critic-1.107_001 / lib / Perl / Critic / Policy / InputOutput / ProhibitExplicitStdin.pm 

            

              
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##############################################################################
#      $URL: http://perlcritic.tigris.org/svn/perlcritic/trunk/distributions/Perl-Critic/lib/Perl/Critic/Policy/InputOutput/ProhibitExplicitStdin.pm $
#     $Date: 2010-06-13 18:26:31 -0500 (Sun, 13 Jun 2010) $
#   $Author: clonezone $
# $Revision: 3824 $
##############################################################################
package Perl::Critic::Policy::InputOutput::ProhibitExplicitStdin;
use 5.006001;
use strict;
use warnings;
use Readonly;
use List::MoreUtils qw(any);
use Perl::Critic::Utils qw{ :severities :classification &parse_arg_list };
use base 'Perl::Critic::Policy';
our $VERSION = '1.107_001';
#-----------------------------------------------------------------------------
Readonly::Scalar my $DESC => q{Use "<>" or "<ARGV>" or a prompting module instead of "<STDIN>"};
Readonly::Scalar my $EXPL => [216,220,221];
#-----------------------------------------------------------------------------
sub supported_parameters { return ()                                }
sub default_severity     { return $SEVERITY_HIGH                    }
sub default_themes       { return qw( core pbp maintenance )        }
sub applies_to           { return 'PPI::Token::QuoteLike::Readline' }
#-----------------------------------------------------------------------------
sub violates {
    my ( $self, $elem, undef ) = @_;
    return if $elem ne '<STDIN>';
    return $self->violation( $DESC, $EXPL, $elem );
}
1;
__END__
#-----------------------------------------------------------------------------
=pod
=head1 NAME
Perl::Critic::Policy::InputOutput::ProhibitExplicitStdin - Use "<>" or "<ARGV>" or a prompting module instead of "<STDIN>".
=head1 AFFILIATION
This Policy is part of the core L<Perl::Critic|Perl::Critic>
distribution.
=head1 DESCRIPTION
Perl has a useful magic filehandle called C<*ARGV> that checks the
command line and if there are any arguments, opens and reads those as
files.  If there are no arguments, C<*ARGV> behaves like C<*STDIN>
instead.  This behavior is almost always what you want if you want to
create a program that reads from C<STDIN>.  This is often written in
one of the following two equivalent forms:
  while (<ARGV>) {
    # ... do something with each input line ...
  }
  # or, equivalently:
  while (<>) {
    # ... do something with each input line ...
  }
If you want to prompt for user input, try special purpose modules like
L<IO::Prompt|IO::Prompt>.
=head1 CONFIGURATION
This Policy is not configurable except for the standard options.
=head1 CAVEATS
Due to a bug in the current version of PPI (v1.119_03) and earlier,
the readline operator is often misinterpreted as less-than and
greater-than operators after a comma.  Therefore, this policy misses
important cases like
  my $content = join '', <STDIN>;
because it interprets that line as the nonsensical statement:
  my $content = join '', < STDIN >;
When that PPI bug is fixed, this policy should start catching those
violations automatically.
=head1 CREDITS
Initial development of this policy was supported by a grant from the
Perl Foundation.
=head1 AUTHOR
Chris Dolan <cdolan@cpan.org>
=head1 COPYRIGHT
Copyright (c) 2007-2010 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
=cut
# Local Variables:
#   mode: cperl
#   cperl-indent-level: 4
#   fill-column: 78
#   indent-tabs-mode: nil
#   c-indentation-style: bsd
# End:
# ex: set ts=8 sts=4 sw=4 tw=78 ft=perl expandtab shiftround :