You are assuming that your code destroys everything in a package properly. Let's test that: 
#! /usr/bin/perl -w
use strict;

my $s;

print "Creating functions\n";
my $x = TellDestroy->new(sub {print $s}, "variable sub");
*Foo::function = TellDestroy->new(sub {print $s}, "glob sub");

print "Clearing variable\n";
undef $x;

print "Clearing glob\n";
undef %Foo::;

print "Exiting\n";

package TellDestroy;
use Scalar::Util qw(refaddr);
my %function_name;

sub new {
  my ($class, $self, $name) = @_;
  $function_name{refaddr($self)} = $name;
  bless $self, $class;
}

sub DESTROY {
  my $self = shift;
  my $name = delete $function_name{ refaddr($self) };
  print STDERR "$name is going away\n";
}
__END__

[download]
produces the following output for me on Perl 5.8.6 under Linux: 
Name "Foo::function" used only once: possible typo at check line 8.
Creating functions
Clearing variable
variable sub is going away
Clearing glob
Exiting
glob sub is going away

[download]
So the function survived to global destruction. I take that to mean that Perl doesn't clean up packages the way you wanted it to.

In reply to Re^3: Overloading different instances differently. by tilly
in thread Overloading different instances differently. by kyle

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