# -*- Perl -*-
package Foo;

use strict;
use warnings;

sub new { bless [], shift }
    
sub warn { shift; warn "[", __PACKAGE__, "] ", @_ }

sub do_cb {
    my ($self, $cb)=@_;
    $self->$cb;
}

1;

__END__

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;
use Foo;

my $f=Foo->new;

$f->do_cb(sub {
    my $caller=shift;
    $caller->warn("no good for me\n");
});

__END__

##</code><code>##

    warn $caller "no good for me\n";