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Re: Timing of garbage collection

by blue_cowdawg (Monsignor)
on Jan 18, 2013 at 18:15 UTC ( #1014102=note: print w/replies, xml ) Need Help??

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.

Peter L. Berghold -- Unix Professional
Peter -at- Berghold -dot- Net; AOL IM redcowdawg Yahoo IM: blue_cowdawg

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Re^2: Timing of garbage collection
by tobyink (Abbot) on Jan 18, 2013 at 18:39 UTC


    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;
    perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'
    /tt); my $B = $A; is(refcount($A), 2,

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