--- /dev/null
+##############################################################################
+# $URL: http://perlcritic.tigris.org/svn/perlcritic/trunk/Perl-Critic/lib/Perl/Critic/Policy/Variables/RequireLocalizedPunctuationVars.pm $
+# $Date: 2008-07-03 10:19:10 -0500 (Thu, 03 Jul 2008) $
+# $Author: clonezone $
+# $Revision: 2489 $
+##############################################################################
+
+package Perl::Critic::Policy::Variables::RequireLocalizedPunctuationVars;
+
+use 5.006001;
+use strict;
+use warnings;
+use Readonly;
+
+use Perl::Critic::Utils qw{ :severities :classification hashify};
+use base 'Perl::Critic::Policy';
+
+our $VERSION = '1.088';
+
+#-----------------------------------------------------------------------------
+
+Readonly::Scalar my $PACKAGE_RX => qr/::/mx;
+Readonly::Hash my %EXCEPTIONS => hashify(qw(
+ $_
+ $ARG
+ @_
+));
+Readonly::Scalar my $DESC => q{Magic variables should be assigned as "local"};
+Readonly::Scalar my $EXPL => [ 81, 82 ];
+
+#-----------------------------------------------------------------------------
+
+sub supported_parameters { return () }
+sub default_severity { return $SEVERITY_HIGH }
+sub default_themes { return qw(core pbp bugs) }
+sub applies_to { return 'PPI::Token::Operator' }
+
+#-----------------------------------------------------------------------------
+
+sub violates {
+ my ( $self, $elem, undef ) = @_;
+
+ return if $elem ne q{=};
+
+ my $destination = $elem->sprevious_sibling;
+ return if !$destination; # huh? assignment in void context??
+
+ if (_is_non_local_magic_dest($destination)) {
+ return $self->violation( $DESC, $EXPL, $elem );
+ }
+ return; # OK
+}
+
+sub _is_non_local_magic_dest {
+ my $elem = shift;
+
+ #print "Test dest $elem, @{[ref $elem]}\n";
+
+ # Quick exit if in good form
+ my $modifier = $elem->sprevious_sibling;
+ return
+ if
+ $modifier
+ && $modifier->isa('PPI::Token::Word')
+ && ($modifier eq 'local' || $modifier eq 'my');
+
+ # Implementation note: Can't rely on PPI::Token::Magic,
+ # unfortunately, because we need English too
+
+ if ($elem->isa('PPI::Token::Symbol')) {
+ return _is_magic_var($elem);
+ } elsif ($elem->isa('PPI::Structure::List') || $elem->isa('PPI::Statement::Expression')) {
+ for my $child ($elem->schildren) {
+ return 1 if _is_non_local_magic_dest($child);
+ }
+ }
+
+ return;
+}
+
+#-----------------------------------------------------------------------------
+
+sub _is_magic_var {
+ my ($elem) = @_;
+
+ my $variable_name = "$elem";
+ return if $EXCEPTIONS{$variable_name};
+ return 1 if $elem->isa('PPI::Token::Magic'); # optimization(?), and helps with PPI 1.118 carat bug
+ return if ! is_perl_global( $elem );
+
+ return 1;
+}
+
+1;
+
+__END__
+
+#-----------------------------------------------------------------------------
+
+=pod
+
+=head1 NAME
+
+Perl::Critic::Policy::Variables::RequireLocalizedPunctuationVars - Magic variables should be assigned as "local".
+
+=head1 AFFILIATION
+
+This Policy is part of the core L<Perl::Critic> distribution.
+
+
+=head1 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 L<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 C<my>. Perl prevents using C<my>
+with "proper" punctuation variables, but allows C<$a>, C<@ARGV>, the
+names declared by L<English>, etc. This is not a good coding
+practice, however it is not the concern of this specific policy to
+complain about that.
+
+
+=head1 CONFIGURATION
+
+This Policy is not configurable except for the standard options.
+
+
+=head1 CAVEATS
+
+The current PPI (v1.118) has a bug where $^ variables absorb following
+whitespace by mistake. This makes it harder to spot those as magic
+variables. Hopefully this will be fixed by PPI 1.200. In the
+meantime, we have a workaround in this module.
+
+Additionally, PPI v1.118 fails to recognize %! and %^H as magic
+variables. PPI instead sees the "%" as a modulus operator. We have
+no workaround for that bug right now.
+
+=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) 2007-2008 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 :
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