Re: self = [super init], nil?
Re: self = [super init], nil?
- Subject: Re: self = [super init], nil?
- From: Flavio Donadio <email@hidden>
- Date: Sat, 8 May 2010 11:00:27 -0300
Patrick,
I made some mistakes in the code. Wherever I wrote +init (or something similar), I really meant -init. It's an instance method, not a class method.
That's what happens when you type code in Mail before having breakfast...
Cheers,
Flavio
On 08/05/2010, at 10:13, Flavio Donadio wrote:
> Patrick,
>
>
> I don't really know if I am right, because of lack of experience. Please, correct me if I'm wrong, but... Why would anyone write code like that?
>
> I mean, if one subclasses NSObject and doesn't override +init, it will return self -- or, maybe, nil -- anyways.
>
> So, I would assume that [super init] would only be called inside an +init or +initWithWhatever: method, right? Like this:
>
> + (id*)init
> {
> [super init];
> // initialize some other instance vars, etc. ...
> [return self];
> }
>
> So, in case a class' +init method can return nil and you want to subclass it, the code should be more like:
>
> + (id*)init
> {
> if ([super init] != nil)
> {
> ...
> [return self];
> }
> else
> {
> return nil; // or return something else, throw an exception, whatever...
> }
> }
>
> I am just curious, because I think it's strange to write "self = [super init]" anywhere other than in an overriden +init. Am I right?
>
>
> Cheers,
> Flavio
>
>
> On 08/05/2010, at 01:23, Patrick M. Rutkowski wrote:
>
>> Will NSObject's init method ever really return nil?
>>
>> E.g. if I sub-class NSObject, then is it worth checking for nil after
>> doing self = [super init]?
>>
>> I know there are many classes in UIKit and Cocoa which most definitely
>> can return nil from their -init's, as an indication of failure. But
>> will this ever be the case with NSObject?
>>
>> -Patrick
>
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