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Date: Sat, 16 Jul 2011 11:14:28 +0100
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Subject: Re: [PHP-DEV] weak references
From: rquadling@gmail.com (Richard Quadling)

On 14 July 2011 20:42, Ferenc Kovacs <tyra3l@gmail.com> wrote:
> To spare the "5.4 features vote" thread from the off-topic discussion,
> we can continue here.
> Hannes Landeholm brought this idea up, see
> http://news.php.net/php.internals/53956 and
> http://news.php.net/php.internals/53959
> I would suggest that Hannes create an rfc, and add some examples and
> introduce the weak references in general and how this can be useful,
> what problems do they solve (it was discussed in the bugreport, but it
> wasn't clear as far as I can tell from the comments).

Not being an expert here, so the questions may have obvious answers.

How often does the gc cycle run during a script?

Can preemptive cleanup actually cause more of a headache?

In reading about weak references on
http://en.wikipedia.org/wiki/Weak_reference, weak references look like
a perfect use case for memory limited caches, but I wonder if there
would be a way of synching a TTL to the weak referenced objects, so
that they essentially automatically expire (or can be expired and
expunged). A system controlled TTL for weak referenced objects.

So,

void SplWeakRef::__construct(object $ref, [int $ttl = -1])

$ttl = -1 would allow the object to be gc'd in the normal way, but any
other value would be a hint to how long the object would be expected
to last for. If gc happens frequently, then $ttl acts as a limiter and
I think this could be very useful.
-- 
Richard Quadling
Twitter : EE : Zend : PHPDoc
@RQuadling : e-e.com/M_248814.html : bit.ly/9O8vFY : bit.ly/lFnVea