Hi Chuck,

On Dec 6, 2008, at 22:36, Charles Steinman wrote:

The system will only call dealloc if the object is released. Happily, the object should be released anyway if you plan to return nil since otherwise you'll leak a half-initialized object every time the method fails. So you should release self and return nil.

I'm not sure about that. Take a look at this example:

// init only modifies an already allocated buffer.
// ObjC and the O/S does not know what you are going to name your 'init' method:

- (id)initIthMyParameters:(int)aParameter
{
  self = [super init];
  if(self) // only if super returns a valid buffer
  {
    parameter = aParameter;
  }
  return(self);
}

ob = [[MyObject alloc] initWithMyParameters:3];

The result of [MyObject alloc] is passed directly to initWithMyParameters:.

If alloc fails, it sends NULL as object to init. [NULL init] returns NULL, no matter which object it is, so does [NULL sniff_sniff]. -However, if +alloc succeeds, you have a buffer, it's passed directly to initWithMyParameters:.

You're not guaranteed that you will get the same buffer that [MyObject alloc] returns, because -init* will be able to deallocate it and return a different (maybe even larger) buffer instead, and perhaps in a different memory zone.

Who/what is supposed to deallocate the allocated buffer between the [MyObject alloc] and [myObject init] ?
(How would the 'system' know that the object is to be deallocated?)
The only reason would be that the line...

  self=NULL;

...should automatically deallocate the object, and I've never heard that it did.

The general rule is: Whatever mess you create (inside your method), you have to cleanup yourself, noone else is doing it for you. -But if you return NULL from -init, you *must* deallocate self first, or you will leak memory.


Love,
Jens

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