Re: [OT] Retain count riddle
Re: [OT] Retain count riddle
- Subject: Re: [OT] Retain count riddle
- From: Stéphane Sudre <email@hidden>
- Date: Tue, 30 Mar 2004 22:10:33 +0200
On mardi, mars 30, 2004, at 09:49 PM, Sailesh Agrawal wrote:
So I had this bug the other day that I thought would make an
interesting
riddle.
The code looked like this:
#define SAFE_SET(old, new) [new retain]; [old release]; old = new;
...
- (void) foo : (NSString*)path {
SAFE_SET(m_Path, [path lastPathComponent]);
}
Now the problem was any time I accessed m_Path my app would crash.
This
isn't cocoa specific, I'm just dumb for using macros where I should
have
been using a function. Can anyone guess what the problem is ?
Too easy.
Your Macro leads to:
old = [path lastPathComponent];
so old points to an autoreleased object.
So next time you try to access the object, the object points to nothing
particular.
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