/ 
Perl-Critic-1.152
River stage three • 131 direct dependents • 411 total dependents
/ Perl::Critic::Policy::Variables::RequireLexicalLoopIterators

NAME

Perl::Critic::Policy::Variables::RequireLexicalLoopIterators - Write for my $element (@list) {...} instead of for $element (@list) {...}.

AFFILIATION

This Policy is part of the core Perl::Critic distribution.

DESCRIPTION

This policy asks you to use my-style lexical loop iterator variables:

foreach my $zed (...) {
    ...
}

Unless you use my, for/foreach loops use a global variable with its value local to the block. In other words,

foreach $zed (...) {
    ...
}

is more-or-less equivalent to

{
    local $zed
    foreach $zed (...) {
        ...
    }
}

This may not seem like a big deal until you see code like

my $bicycle;
for $bicycle (@things_attached_to_the_bike_rack) {
    if (
            $bicycle->is_red()
        and $bicycle->has_baseball_card_in_spokes()
        and $bicycle->has_bent_kickstand()
    ) {
        $bicycle->remove_lock();

        last;
    }
}

if ( $bicycle and $bicycle->is_unlocked() ) {
    ride_home($bicycle);
}

which is not going to allow you to arrive in time for dinner with your family because the $bicycle outside the loop is not changed by the loop. You may have unlocked your bicycle, but you can't remember which one it was.

Lexical loop variables were introduced in Perl 5.004. This policy does not report violations on code which explicitly specifies an earlier version of Perl (e.g. require 5.002;).

CONFIGURATION

This Policy is not configurable except for the standard options.

SEE ALSO

"Foreach Loops" in perlsyn

"my() in Control Structures" in perl5004delta

AUTHOR

Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>

COPYRIGHT

Copyright (c) 2005-2023 Imaginative Software Systems

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.