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

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

Mic,

You cannot refer to the class directly in Objective-C, that's because  
PyObjC will create the class at runtime and your ObjC code tries to  
link to it at compile-time.

I tend to write all my code in Python, using ObjC as a way to optimize  
code where needed and to access API's that are not available in  
Python.  This means I tend to be able to get away with creating  
instances in Python code, while still calling methods on them in ObjC.

Ronald

On 10 May, 2009, at 18:26, Mic Pringle wrote:

> Hi Ronald,
>
> As you have probably seen, I now have categories working fine, thanks
> to your help.
>
> You mentioned in one of your earlier replies that I can also do the
> same for subclasses, not just categories. So following this I have
> created a header file in Objective-C with the following contents ...
>
> #import <Cocoa/Cocoa.h>
>
> @interface BKTextile : NSObject
>
> - (NSString *)decodeTextile:(NSString *)aString;
>
> @end
>
> And then created the following Python implementation ...
>
> from Foundation import *
> import textile
>
> class BKTextile(NSObject):
> 	
> 	def decodeTextile_(self, aString):
> 		return u"it worked!"
>
> Which is pretty much what I've done to get the category to work,
> except when I try to compile I get the following error ...
>
> .objc_class_name_BKTextile referenced from:
> literal-pointer@_OBJC@__cls_refs@BKTextile in PythonServerTest.o
> symbol(s) not found
>
> Any ideas ??
>
> Thanks,
>
> Mic
>
>
> 2009/5/8 Ronald Oussoren <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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>>