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Re: State of instance variables defined at instantiation?
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Re: State of instance variables defined at instantiation?


  • Subject: Re: State of instance variables defined at instantiation?
  • From: Ben Dougall <email@hidden>
  • Date: Tue, 27 May 2003 14:14:13 +0100

On Tuesday, May 27, 2003, at 03:57 am, Wade Tregaskis wrote:

from what i know it actually occurs during alloc, so occurs before init. what i'd like to know is if you want all internal variables set to 0, is init necessary? what else does init do, if anything other than set variables up?

Well, it's created a dependency for itself through it's own existence. When you create an object using a generic allocation routine (e.g. alloc) you should call at the very least it's generic 'init' method, to allow it to set up any non-nil parameters, or perform any other appropriate instantiation.

Unfortunately, the result is that if you don't define a generic init method, and someone using the class tries to do the nice thing and call [[yourClass alloc] init], they'll get thrown a compiler warning. So you have to define a useless init method, like the following:

- (object*)init {
return (self = [super init]);
}

This is only a problem if you don't provide other init methods. In such a case, the user should probably be using them anyway, and so the lack of a generic init method would be unimportant.

ok, thanks. is there ever a time that you can get away with just alloc-ing an object, and not init-ing it? and continue as usual?
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