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




> On Aug 8, 2017, at 12:35 PM, Quincey Morris
> <[email protected]> wrote:
>
> I don’t have a problem with using “new” vs. alloc/init, but there are a
> couple of technical issues hiding behind this, though in current practice
> they make little difference.
>
> 1. NSObject has “new” with a standard meaning. That means you can use “new”
> on any subclass where it’s OK to use the simple “init” without parameters.
> However, for classes that need parameters, or have multiple inits, there’s no
> standard “newWithX:…” class method unless you provide it yourself.
>
> You can’t really provide this for Cocoa classes (you could try adding it via
> a category, but this seems like a bad idea), which means your code uses a
> mixture of strategies to create instances, even of the same class, depending
> on the parameters needed. If that doesn’t bother you, fine. This is purely a
> matter of preference.
>
> 2. In modern Obj-C, a class method beginning with “new…” is specially
> meaningful to the compiler under ARC. By default, it has +1 ownership
> semantics for the returned reference. Using Jens’ earlier example, that means
> that the following are subtly different:
>
>> [NSArray array] // +0 semantics
>> [NSArray new] // +1 semantics
>
> For custom “new…” methods, the declaration can override the default semantics
> with a compile-time attribute, which means you cannot in general be certain
> of ...

the semantics without looking at the declaration.

>
> Of course, if the *calling* code is also ARC, then it doesn’t matter, because
> ARC keeps track of the semantics for you.


Thank you. These concerns are exactly what I was looking for. Thanks for
expressing them much better than I could.





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