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Proposed rules of thumb, with discussion.

The question here is, “what if my delegate is released? I’ll get a segfault!” That’s a good question, I think. your delegate object should then unhook itself in its dealloc method. same way it unregisters itself from the notification center. Otherwise the object holding the delegate will hang on to send messages to an object that otherwise should have gone away

See DelegationAndNotification for an example of why objects retaining their delegates is a bad idea. Delegates and delegators are peer objects - there’s no ownership status implied.

Are the following rules of thumb?

This is a horrible thing to call a rule of thumb. How about “If you alloc, retain, or copy it, it’s your job to release it. Otherwise it isn’t.” instead?

*-I knew this would be not very welcomed! I think both should be rules of thumb; the use of autorelease makes the alloc-retain thing much easier, and I think is meant to be widely used, and for sure makes your life easier and safer at the development stage; I did not realize it until I read the ‘indifferent 2’ section of this page: and found what is said here is so true… –CharlesParnot *

Yeah, I’d say this is a good rule of thumb. I was initially taken aback as well, but it makes sense. The alloc, retain, copy thing isn’t really something you have any discretion about, though.

It’s not a good rule, especially as it now reads, the emphasis is on creating many objects (I know this wasn’t the authors intention, but it’s very easy to misinterpret). Perhaps the rule of thumb should be to use convenience constructors instead of the alloc-init calls, when there is an option. Otherwise it’s a silly thing to say, why should I autorelease all my objects, when it’s just as easy to release them when I’m done with them? –TheoHultberg/Iconara

One good reason is for when you edit your code later and include a return statement. You might bypass the release. Also, I notice that I sometimes write an alloc/init without writing a corresponding release.

Exactly. I think this is at least very convenient to use autorelease a lot when developing: it minimize errors, and also minimizes the amount of rewrite you have to do (removing an init-alloc takes two lines). Finally, the memory issue I was refering too can translate into a performance issue, I agree. In which case you want to then clean up the code, use mutable objects, etc… –CharlesParnot

What’s a simple rule of thumb for where to release/autorelease?

In some cases, the auto-/release should come in the same block. In others, it should be in the dealloc method. In still others, methods might come in pairs, with the copy/alloc/retain in one and the auto-/release in the other. For an example of the last case, consider a delegate used by some tree traversing algorithm, such as XML parsing, that sends messages when starting and ending node processing. When the delegate visits a particular node, it creates some ancillary data. When finished with the node, the delegate releases the ancillary data. How can we describe this balance? Is there a simple rule that describes all these cases and others? –outis Pour devenir figurant sur garder le numéro, vous aurez compte propriétaire ( signal ) [ numéro rio]. Vous obtiendrez pour totalement gratuit par téléphonant du serveur ou du service à la clientèle clientèle partir de votre vieille fournisseur [ code rio bouygues] . Vous ne obtenir un SMS avec votre . Avec votre [ numero rio orange], alors il est possible d’ la offre de votre à propos citrons .