I figured out something that doesn't SEEM to use globals, but it probably does something much worse...

Run this and hit CTRL-C, it will print how many seconds it thinks it's been running

#! /usr/bin/perl -w -T

use strict;

my $var;

($var,$SIG{INT}) = voodoo();

sub voodoo {
        my $thing ;
        my $sub = sub {
                my $blob = \$thing;
                print $$blob."\n";
                exit;
        };
        return (\$thing,$sub);
}

for (my $i=0; $i<60 ;$i++) {
        $$var = $i;
        sleep 1;
}
[download]

Let me know what sort of terrible thing I've done...

You're forming a closure on $thing, as well as returning a reference to it. voodoo() indeed!

One nice way to pretend you don't have a global variable when you do (I've talked about this one before):

{
    my $foo;
    sub foo () :lvalue { $foo }
}

foo = 'bar';
print foo, $/;
[download]

No sigil, that makes some people happy ;-)

After Compline,
Zaxo

In general, lexical closures are a handy and useful technique, but I'm not entirely sure what interesting edge cases will emerge if you combine them with signal handlers. I wouldn't care to speculate on that without understanding the nittier and grittier details of how signal handlers are handled.

What I would do is name the global in a fashion that prevents it from ever having a namespace collision and then just leave it global. For instance, I might call it something like $SIGINT_HANDLER_GLOBAL_ONE_FOR_NET_SERVER_POP3 (if it were the first global variable for the interrupt signal handler for Net::Server::POP3; as it happens that module doesn't have any such thing, but you get the idea).