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package Perl::Critic::Policy::Community::Each;
use strict;
use warnings;
use Perl::Critic::Utils qw(:severities :classification :ppi);
use parent 'Perl::Critic::Policy';
our $VERSION = 'v1.0.4';
use constant DESC => 'each() called';
use constant EXPL => 'The each function may cause undefined behavior when operating on the hash while iterating. Use a foreach loop over the hash\'s keys or values instead.';
sub supported_parameters { () }
sub default_severity { $SEVERITY_LOW }
sub default_themes { 'community' }
sub applies_to { 'PPI::Token::Word' }
sub violates {
my ($self, $elem) = @_;
return () unless $elem eq 'each' and is_function_call $elem;
return $self->violation(DESC, EXPL, $elem);
}
1;
=head1 NAME
Perl::Critic::Policy::Community::Each - Don't use each to iterate through a
hash
=head1 DESCRIPTION
The C<each()> function relies on an iterator internal to a hash (or array),
which is the same iterator used by C<keys()> and C<values()>. So deleting or
adding hash elements during iteration, or just calling C<keys()> or C<values()>
on the hash, will cause undefined behavior and the code will likely break. This
could occur even by passing the hash to other functions which operate on the
hash. Instead, use a C<foreach> loop iterating through the keys or values of
the hash.
while (my ($key, $value) = each %hash) { ... } # not ok
foreach my $key (keys %hash) { my $value = $hash{$key}; ... } # ok
foreach my $i (0..$#array) { my $elem = $array[$i]; ... } # ok
=head1 AFFILIATION
This policy is part of L<Perl::Critic::Community>.
=head1 CONFIGURATION
This policy is not configurable except for the standard options.
=head1 AUTHOR
Dan Book, C<dbook@cpan.org>
=head1 COPYRIGHT AND LICENSE
Copyright 2015, Dan Book.
This library is free software; you may redistribute it and/or modify it under
the terms of the Artistic License version 2.0.
=head1 SEE ALSO
L<Perl::Critic>, L<http://blogs.perl.org/users/rurban/2014/04/do-not-use-each.html>
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