Re: Accessors Question
Re: Accessors Question
- Subject: Re: Accessors Question
- From: Jean-Daniel Dupas <email@hidden>
- Date: Thu, 12 Jun 2008 19:31:14 +0200
Le 12 juin 08 à 19:21, Jeff LaMarche a écrit :
Lately, I've started to see accessors of the following sort:
- (NSString *)foo
{
return [[foo retain] autorelease];
}
rather than just
- (NSString *)foo
{
return foo;
}
What is the purpose or benefit of doing this? It seems to me that
this would add things unnecessarily to the autorelease pool, and I
can't see a benefit to be had. I've seen it in places that make me
think there must be a reason (e.g. sample code from Apple), so I'm
guessing I'm missing something. Is there some benefit due to GC? If
so, should this construct be used without GC or only with?
Thanks,
Jeff
I think the purpose is describe in the "writing accessor" guide :
http://developer.apple.com/documentation/Cocoa/Conceptual/MemoryMgmt/Articles/mmAccessorMethods.html
"As with values manufactured by class convenience methods, the
returned object is autoreleased in the current scope and thus remains
valid if the property value is changed.”
This is mainly to prevent this kind of issue:
NSString *foo = [myObject foo];
[myObject setFoo:nil]; // setter release the foo ivar => foo is no
longer pointing on a valid memory location.
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