Re: [Pyobjc-dev] Access to 'hidden' class-methods

[Ronald O. <ous...@ci...>]

On Sunday, Jan 12, 2003, at 22:36 Europe/Amsterdam, Jack Jansen wrote:

>
> On zondag, jan 12, 2003, at 20:36 Europe/Amsterdam, Ronald Oussoren 
> wrote:
>>
>> Right. A class is an instance of its meta-class and class-methods are 
>> in fact normal methods of the meta-class [...]
>
> Are you sure this is the case? Then how can I access "self" in a class 
> method (which would be the class)? Or is the only reason I can't get 
> at self in a class method is that the ObjC syntactic sugar doesn't 
> allow it?
You can, but inside a class method 'self' refers to the class instead 
of instances of the class.

$ cat t.m
#include <Foundation/Foundation.h>

@interface TestClass :NSObject
{
}

+classMethod;

@end

@implementation TestClass

+classMethod
{
         printf("%p: Self of class method\n", self);
         printf("%p: Class TestClass\n", [TestClass class]);
         return 0;
}
@end

int main(void)
{
         [TestClass classMethod];
}

$ cc -o t t.m -framework Foundation
$ ./t
0x400c: Self of class method
0x400c: Class TestClass


>
> Hmm, another wild idea: would this mean that by declaring a category 
> on the metaclass you could influence creation of all ObjC objects?
You probably could, but: the metaclass has the same name as the normal 
class which makes it hard to define a category on it. But is guess 
defining a category containing class-mehods on a normal class would do 
what you want.

Ronald