Re: Property Declared in a Category and Sent to id
Re: Property Declared in a Category and Sent to id
- Subject: Re: Property Declared in a Category and Sent to id
- From: Andreas Grosam <email@hidden>
- Date: Mon, 17 Dec 2012 12:20:19 +0100
On 17.12.2012, at 11:25, Andreas Grosam wrote:
> I would like to use the property access syntax for a (readonly) property which is defined in a category and sent to an object whose compile type info is just "id". Use case:
>
> id obj = …;
> if (obj.isFoo) { // <== error: property 'isFoo' not found for object of type '__strong id'.
> ...
> }
>
>
> So, why does message send syntax compiles fine - but property syntax not??
Well, after thinking a while about the issue, I can answer this myself:
The compiler requires the type information in order to figure the actual getter signature. When declaring the a property, the getter and setter may be explicitly specified, for example:
@property (readonly, getter=getFooStateOrWhatever) isFoo;
Thus, the compiler cannot deduce the setter and getter methods from the property name unless it knows the type. So, in the case above where the type is not known at compile time, I cannot use dot syntax but needs to use method send syntax with the actual getter signature.
Andreas
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