Re: coderefs keep references to themselves

Actually its the other way round; the destroy doesn't happen because its not a closure. For non-closure anonymous subs, perl just shares the same internal CV structure among all the code refs to the sub

As soon as you make the sub a closure (by referring to an external lexical var), it starts to behave the way you expect:

$ perl -e 'my $z; my $x = sub { $z; "test" };  bless $x, "HRM"; sub HR
+M::DESTROY { print "bye\n" };'
bye
$
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Dave.

Comment on Re: coderefs keep references to themselves Download Code

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Re^2: coderefs keep references to themselves by jettero (Monsignor) on Jul 15, 2008 at 12:02 UTC
Curious. I definitely don't understand how using $z in $x makes $x point to $x less. -Paul	[reply]
Re^3: coderefs keep references to themselves by Fletch (Bishop) on Jul 15, 2008 at 13:00 UTC
It's because there's a reference to a variable in the enclosing scope (`$z`) that it's actually now a closure. Before it had no ties to any variables in the enclosing scope so it wasn't a closure triggering the optimization. Adding `$z` means that it now does reference a var in the enclosing scope and won't trigger the optimization and now the destructor is called. If yours (or his) had referenced `$x` (although you'd have to make the declaration and assignments two steps (e.g. `my $x; $x = sub { $x; "test" }`)) then `$x` would have served the same purpose; as is `$x` never enters into the closure/not-closure picture because your lexical `$x` isn't referenced from your anonymous sub. The cake is a lie. The cake is a lie. The cake is a lie.	[reply] [d/l] [select]