Collection Object

[Shaun Wexler]

On Aug 3, 2006, at 1:08 AM, Ruslan Zasukhin wrote:

> Does objC do at runtime string compare of name method for an  
> instance to
> find if this object have this or that method ?

Yes and no.  An object exists in memory like this (pseudo):

     typedef const char *SEL; // method name
     typedef struct objc_class *Class;
     typedef Class *id;

     struct Object {
         Class isa;
     } Object;

     class MyDirectObjectSubclass : Object {
         id something;
         char string[4];
	void *etc;
     }

Dispatching a message is simply a function call with predefined arg's:

    retval = (*methodIMP)(id self, SEL _cmd, args...);


The "magic" is how the methodIMP* is first resolved:  quick lookup in  
objc_class method cache buckets, else by linear method-table search,  
keyed by the SEL (which only compares its void* value, rather than by  
strcmp).

The approach I would like to take for the forthcoming Valentina 3  
versions is to toll-free bridge the C++ FBL classes with CF/NS.  I  
know can do it!  I have the power...  ;)
-- 
Shaun Wexler
MacFOH
http://www.macfoh.com