Re^2: No DESTROY object.

[gam3]

There are 2 problems with your argument that jump out at me.

1. first - DESTROY should still get called even if only once.
2. second sub { $bob } does not get DESTROYed either and it certainly not immutable.

package Foo;
sub print { print "@_\n"; }
sub DESTROY {
   print "@_ DESTROY\n";
}
our $bob = "x\n";
my $x = bless(sub {$bob}, 'Foo');
$x->print('$bob');
print $x->();
$bob = "y\n";
print $x->();
$bob = undef;
__END__
Foo=CODE(0xe8a278) $bob
x
y

[ambrus]

For your second question, if you replace our $bob to my $bob, then the DESTROY does get called. This way, perl knows that $bob is a global so it optimizes the sub constructor to a constant again.