Re: Timing of garbage collection

[blue_cowdawg]

in reply to Timing of garbage collection

So, just how undesirable is it to manually call object destructors?

I heard Larry Wall talk about GC in Perl about eleven years ago and I'll paraphrase him here: "Something lives in memory in Perl until nobody cares."

From what I remember there is a reference count associated with any variable (or object) and when that reference counter drops to zero the object is freed from memory.

[tobyink]

Indeed...

use strict;
use warnings;
use Test::More;

use Scalar::Util qw(weaken isweak);
use Devel::Refcount qw(refcount);

my $A = bless {}, 'Monkey';
is(refcount($A), 1, 'an object has a refcount');

my $B = $A;
is(refcount($A), 2, 'additional ref to the object increases the refcou
+nt');

$B = undef;
is(refcount($A), 1, 'removing a ref to the object decreases the refcou
+nt');

do {
    my $C = $A;
    is(refcount($A), 2, 'reference in a scope increases refcount');
};

is(refcount($A), 1, '$C fell out of scope, so decreased ref count');

my $D = $A;
is(refcount($A), 2, 'another ref which will increase ref count');

weaken $D;
is(refcount($A), 1, 'weakening the ref means it is not included in the
+ ref count');
ok($A == $D, 'yet $A and $D are still the same object');

my $destroyed = 0;
sub Monkey::DESTROY { $destroyed++ };

$A = undef;
is($destroyed, 1, 'undefining $A destroyed the object; $D was a weak r
+ef so did not prevent destruction');

ok(!defined $D, '$D is now undefined');

done_testing;

/tt); my $B = $A; is(refcount($A), 2,