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.IX Title "Perl::Critic::Policy::Variables::RequireLexicalLoopIterators 3pm"
.TH Perl::Critic::Policy::Variables::RequireLexicalLoopIterators 3pm 2023-07-26 "perl v5.38.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.if n .ad l
.nh
.SH NAME
Perl::Critic::Policy::Variables::RequireLexicalLoopIterators \- Write "for my $element (@list) {...}" instead of "for $element (@list) {...}".
.SH AFFILIATION
.IX Header "AFFILIATION"
This Policy is part of the core Perl::Critic
distribution.
.SH DESCRIPTION
.IX Header "DESCRIPTION"
This policy asks you to use \f(CW\*(C`my\*(C'\fR\-style lexical loop iterator variables:
.PP
.Vb 3
\&    foreach my $zed (...) {
\&        ...
\&    }
.Ve
.PP
Unless you use \f(CW\*(C`my\*(C'\fR, \f(CW\*(C`for\*(C'\fR/\f(CW\*(C`foreach\*(C'\fR loops use a global variable with
its value \f(CW\*(C`local\*(C'\fR to the block. In other words,
.PP
.Vb 3
\&    foreach $zed (...) {
\&        ...
\&    }
.Ve
.PP
is more-or-less equivalent to
.PP
.Vb 6
\&    {
\&        local $zed
\&        foreach $zed (...) {
\&            ...
\&        }
\&    }
.Ve
.PP
This may not seem like a big deal until you see code like
.PP
.Vb 8
\&    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);
\&    }
.Ve
.PP
which is not going to allow you to arrive in time for dinner with your
family because the \f(CW$bicycle\fR outside the loop is not changed by the
loop. You may have unlocked your bicycle, but you can't remember which
one it was.
.PP
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. \f(CW\*(C`require 5.002;\*(C'\fR).
.SH CONFIGURATION
.IX Header "CONFIGURATION"
This Policy is not configurable except for the standard options.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
"Foreach Loops" in perlsyn
.PP
"\fBmy()\fR in Control Structures" in perl5004delta
.SH AUTHOR
.IX Header "AUTHOR"
Jeffrey Ryan Thalhammer <jeff@imaginative\-software.com>
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright (c) 2005\-2011 Imaginative Software Systems.  All rights reserved.
.PP
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.