Perl::Critic::Policy::Variables::RequireLexicalLoopIterators3pm

Affiliation

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

Overview

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.