Hi

I'm not an expert on Tkx, but I think you might get bitten by the way closure variables are "shared".

Please compare

use strict;
use warnings;


# ---------- for each @list

my @each;

for my $i ( 1..3 ) {
    push @each, sub { warn "each: \t$i" };
}

$_->() for @each;


# ---------- for c-style

my @cfor;

for ( my $i = 1 ; $i < 4; $i++ ) {
    push @cfor, sub { warn "cfor: \t$i" };
}

$_->() for @cfor;


# ---------- generator

sub gen {
    my ($x)=@_;
    return sub { warn "gen: \t$x" };
}

my @gen;

for ( my $i = 1 ; $i < 4; $i++ ) {
    push @gen, gen($i);
}

$_->() for @gen;
[download]

each:     1 at d:/exp/pm_closure.pl line 10.
each:     2 at d:/exp/pm_closure.pl line 10.
each:     3 at d:/exp/pm_closure.pl line 10.
cfor:     4 at d:/exp/pm_closure.pl line 21.
cfor:     4 at d:/exp/pm_closure.pl line 21.
cfor:     4 at d:/exp/pm_closure.pl line 21.
gen:     1 at d:/exp/pm_closure.pl line 31.
gen:     2 at d:/exp/pm_closure.pl line 31.
gen:     3 at d:/exp/pm_closure.pl line 31.
[download]

actually your case with a c-style loop is how it's supposed to be, your my $x has only one instance and only gets a new value with each iteration.²

for (@list)' is special because the loop var is an alias to the list-value. °

To avoid such confusions it's always safe to call a "generator" sub which returns a closure.

footnotes

°) the source of the famous "want stay shared" error. (UPDATE or because it's considered an inside declaration ?)

²) a c-style for is semantically just a while-loop with a prior declaration.

updates

expanded example with clearer output and generator case

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.