Perl::Critic::Policy::Variables::RequireLexicalLoopIterators(3pm)

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.