On 4 Nov 2010, at 7:23 AM, Jonny Taylor wrote:
> If instead I write:
> [(MyClassA*)[MyClassA alloc] initForCamera:cam];
> then I do not get a warning. This leads me to believe that what I am writing
> is not actually doing anything wrong, and the compiler warning is associated
> with the fact that [MyClassA alloc] returns a plain id leaving the compiler
> to do some deducing about what the type actually is. This, combined with the
> confusion of having two methods (for different classes) with the same name
> but different parameter types, seems to be confusing things.
>
> One workaround is to include explicit casts like I have shown. However this
> leaves me wondering whether it goes against convention and/or recommendations
> to have two init methods with the same name but different parameter types,
> even for two unrelated different classes (hard to enforce - one could imagine
> completely different codebases colliding by chance in this respect). Can
> anybody comment on this?
Your assessment is completely correct.
Whether you can live with two initializers with the same selector but different
parameter types is up to you. As you say, you can't in principle avoid such
collisions. Casting is particularly important in the case where the parameters
differ among pointer, scalar, and struct types — then the generated code for
the call is (can be) different, and if the compiler passed them, the resulting
bugs could be inscrutable.
I guess the solution that gives you the best chance of avoiding collisions
without casting is to give the two methods signatures you can hope are unique:
initQICameraForCamera:, initPSCameraForCamera:. But that's still not an
in-principle solution.
Me, I'd wait for warnings, and cast when I need to.
— F
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