Re: [Pyobjc-dev] Catergory Question ...

[Ronald O. <ron...@ma...>]

 
On Friday, May 08, 2009, at 10:59AM, "Mic Pringle" <mic...@gm...> wrote:
>Hi,
>
>Just a quick question regarding categories.
>
>I have a hybrid Obj-c/PyObj-c application and I'd like to know if I
>add a category in a PyObj-c module, will it be availble to use in the
>Obj-c side of the project ??
>
>If so, does it just work or are there any special instructions I need
>to follow to get it working ?

Methods you add using an Python category are available in ObjC as well (the same is true for methods you add in a subclass, those can be called from ObjC as well).

Two possible sources for confusion/problems:

* Unless the methods you add are already known to the compiler you'll have to write a header file that the ObjC compiler
  can use. You'll get compiler warnings otherwise.

* Methods that you add in python by default have arguments and a return value of type 'id'. This can be overridden by:

   - information extracted from the superclass (if you override a method PyObjC knows the new method should have the
     same signature as the one in a superclass).
   - the method is defined in an informal_protocol that's known to PyObjC, the method signature is then extracted from
     that protocol
   - manual annotations (objc.accessor, objc.selector, ....)

Ronald
>Thanks
>
>-Mic
>
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