Event, ithreads, and shared variables

hi perl-loop.  i'm attempting to use Event, ithreads, and shared variables together.  perl is 5.8.3, Event is 0.87.  in particular, i'd like to create a watcher that watches a shared variable.  sample code:

#!/usr/bin/perl
use warnings;
use strict;

use threads;
use threads::shared;

my $data : shared = 0; # the shared variable

#BEGIN {
    my $writer = new threads ( sub {
        while (1) {
            $data++;
            print "write: $data (ref is " . \$data . ")\n";
            sleep (2);
        } } );
#} # end of BEGIN block

use Event;

Event->var (var  => \$data,
            poll => "w",
            cb   => sub { print "read: $data (ref is " . \$data . ")\n"; } )
    or die "can't register variable watcher";

Event->timer ( interval => 2,
               cb => sub { print "timer: $data (ref is " . \$data . ")\n"; } )
    or die "can't register timer";

Event::loop ();

... and some output:

[561] hx@hmb-laptop ~ $ ./foo.pl 
write: 1 (ref is SCALAR(0x102b0220))
timer: 1 (ref is SCALAR(0x1012bcf8))
write: 2 (ref is SCALAR(0x102b0220))
timer: 2 (ref is SCALAR(0x1012bcf8))
write: 3 (ref is SCALAR(0x102b0220))
timer: 3 (ref is SCALAR(0x1012bcf8))
...

the thing to notice is that the variable watcher never triggers.  i guess that might make sense because the references are different.  (that's a guess since i don't really know how var watchers are implemented.)

how can one create a watcher that watches a shared variable?

tia,
-h


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