RE: NSMutableString question
RE: NSMutableString question
- Subject: RE: NSMutableString question
- From: "Matthew Youney" <email@hidden>
- Date: Wed, 17 Sep 2008 11:11:00 -0400
- Importance: Normal
Roland,
You really need to start here:
http://developer.apple.com/documentation/Cocoa/Conceptual/MemoryMgmt/Concept
s/ObjectOwnership.html#//apple_ref/doc/uid/20000043
For me, this was the most complicated part of Cocoa and most different from
other languages. I recommend reading it, printing it, and keeping it next
to you while coding until it is second nature. Trust me that it is easier
learning the rules now rather than hunting Zombies (look it up), and
troubleshooting leaky code later on.
There are some fundamental rules that you must follow. Reading all of this
stuff, it seems quite complicated, however once you learn to "play by the
rules", it makes good sense.
Enjoy,
Matt
-----Original Message-----
From: cocoa-dev-bounces+matt=email@hidden
[mailto:cocoa-dev-bounces+matt=email@hidden]On Behalf Of Bill
Bumgarner
Sent: Tuesday, September 16, 2008 10:50 PM
To: Roland King
Cc: Cocoa Developers
Subject: Re: NSMutableString question
On Sep 16, 2008, at 7:41 PM, Roland King wrote:
> Jason Coco wrote:
>
>>
>> NSMutableString *str = [[NSMutableString alloc] Â
>> initWithCapacity:someAssumedCapacity];
>> /* do stuff */
>> [str release];
>>
> Is that actually guaranteed to release the string *right now*? I
> only ask because I seem to recall a message a couple of months ago
> about a more complicated object where it appeared that the
> initializer did a retain/autorelease on the object so it ended up in
> the autorelease pool before you even got hold of it. That was not an
> object obtained from a convenience method either IIRC, it was a
> [ [ SomeClass alloc ] initConstructorOfSomeSort ] call.
As far as the caller of -release is concerned, that is guaranteed to
release the string *right now*. I.e. the retain implied by +alloc
will be released.
That is all that it guarantees.
The pattern you describe would be an internal implementation detail.
An odd one, at that. But nothing you, the caller, can really do
anything about safely and without breaking encapsulation.
> Unlikely the case with NSMutableString I'd think, but perhaps for
> other things.
>
> The local autorelease pool version I'd think is guaranteed to work.
No more so than -release. All -autorelease does is add the object to
the NSAutoreleasePool, which will send -release when it is -drain'ed.
If the instance does something goofy internally or, in the more common
case, if something else holds a -retain, the object will not be
deallocated upon -drain of the autorelease pool.
b.bum
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