Subject: Re: Is "-init" really needed?



> On Aug 9, 2017, at 3:01 AM, Alastair Houghton <[email protected]>
> wrote:
>
> On 8 Aug 2017, at 17:38, Doug Hill <[email protected]> wrote:
>>
>> As others have mentioned, I too have never seen any evidence or statements
>> from Apple that discourages +new or -init.
>
> I suspect it was ObjC programmers themselves rather than Apple/NeXT that
> discouraged it. As for why, well I can imagine a few reasons:
>
> - Performance - it incurs an extra message send (which would have been an
> issue back in the day)

+new requires no extra message. It's just a shorthand for [[SomeClassname
alloc] init]

> - Clarity - [[… alloc] init] shows clearly that it’s a two step operation
> (some classes support being *re*-initialized, so you can call initialisers
> more than once; other classes don’t actually need initialising)

Some say that it's far more confusing and hard to read the alloc/init syntax.

> - If +new was the way to go, you’d need variants of +new for each variant of
> -init (or you have to use [[… alloc] init] anyway)

There has never been an issue with this. +new saves you some typing for one
syntax but has no impact on anything else.

> - The fact that convenience constructors were often written naming the
> object, e.g. [NSString stringWithFormat:…], [NSArray array]. +new would
> duplicate that, but isn’t as nice to read or look at. OK, +new doesn’t
> autorelease, but still.

With ARC, autorelease behavior is essentially hidden from the developer and
doesn't really matter any more. Again, +new is unrelated to all the other class
methods.

...

Doug Hill
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