--- /dev/null
+##############################################################################
+# $URL: http://perlcritic.tigris.org/svn/perlcritic/trunk/Perl-Critic/lib/Perl/Critic/Policy/InputOutput/ProhibitBacktickOperators.pm $
+# $Date: 2008-07-03 10:19:10 -0500 (Thu, 03 Jul 2008) $
+# $Author: clonezone $
+# $Revision: 2489 $
+##############################################################################
+
+package Perl::Critic::Policy::InputOutput::ProhibitBacktickOperators;
+
+use 5.006001;
+use strict;
+use warnings;
+use Readonly;
+
+use Perl::Critic::Utils qw{ :severities is_in_void_context };
+
+use base 'Perl::Critic::Policy';
+
+our $VERSION = '1.088';
+
+#-----------------------------------------------------------------------------
+
+Readonly::Scalar my $EXPL => q{Use IPC::Open3 instead};
+Readonly::Scalar my $DESC => q{Backtick operator used};
+
+Readonly::Scalar my $VOID_EXPL => q{Assign result to a variable or use system() instead};
+Readonly::Scalar my $VOID_DESC => q{Backtick operator used in void context};
+
+#-----------------------------------------------------------------------------
+
+sub supported_parameters {
+ return (
+ {
+ name => 'only_in_void_context',
+ description => 'Allow backticks everywhere except in void contexts.',
+ behavior => 'boolean',
+ },
+ );
+}
+
+sub default_severity { return $SEVERITY_MEDIUM }
+sub default_themes { return qw(core maintenance) }
+sub applies_to { return qw(PPI::Token::QuoteLike::Backtick
+ PPI::Token::QuoteLike::Command ) }
+
+#-----------------------------------------------------------------------------
+
+sub violates {
+ my ( $self, $elem, undef ) = @_;
+
+ if ( $self->{_only_in_void_context} ) {
+ return if not is_in_void_context( $elem );
+
+ return $self->violation( $VOID_DESC, $VOID_EXPL, $elem );
+ }
+
+ return $self->violation( $DESC, $EXPL, $elem );
+}
+
+1;
+
+__END__
+
+#-----------------------------------------------------------------------------
+
+=pod
+
+=head1 NAME
+
+Perl::Critic::Policy::InputOutput::ProhibitBacktickOperators - Discourage stuff like C<@files = `ls $directory`>.
+
+=head1 AFFILIATION
+
+This Policy is part of the core L<Perl::Critic> distribution.
+
+
+=head1 DESCRIPTION
+
+Backticks are super-convenient, especially for CGI programs, but I
+find that they make a lot of noise by filling up STDERR with messages
+when they fail. I think its better to use IPC::Open3 to trap all the
+output and let the application decide what to do with it.
+
+ use IPC::Open3 'open3';
+ $SIG{CHLD} = 'IGNORE';
+
+ @output = `some_command`; #not ok
+
+ my ($writer, $reader, $err);
+ open3($writer, $reader, $err, 'some_command'); #ok;
+ @output = <$reader>; #Output here
+ @errors = <$err>; #Errors here, instead of the console
+
+
+=head1 CONFIGURATION
+
+Alternatively, if you do want to use backticks, you can restrict
+checks to void contexts by adding the following to your
+F<.perlcriticrc> file:
+
+ [InputOutput::ProhibitBacktickOperators]
+ only_in_void_context = 1
+
+The purpose of backticks is to capture the output of an external
+command. Use of them in a void context is likely a bug. If the
+output isn't actually required, C<system()> should be used. Otherwise
+assign the result to a variable.
+
+ `some_command`; #not ok
+ $output = `some_command`; #ok
+ @output = `some_command`; #ok
+
+
+=head1 NOTES
+
+This policy also prohibits the generalized form of backticks seen as
+C<qx{}>.
+
+See L<perlipc> for more discussion on using C<wait()> instead of
+C<$SIG{CHLD} = 'IGNORE'>.
+
+=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
+
+# 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 :