Re: Callbacks

[Richard Frith-Macdonald]

On Monday, March 3, 2003, at 12:17  am, Philip Mötteli wrote:

> Hi
>
>
> I have the problem, that a framework, that I have to port to 
> Linux/Gnustep, makes use of Apples CoreFoundation library. Actually 
> only one feature of the CoreFoundation is used: Callbacks.
> Those are all these methods, that are called when we insert an object 
> into a collection object: -retain, -release and -copy. So with 
> CoreFoundation one can define, which method in which case should be 
> called. E. g., the "copy-case" could actually call a -retain instead 
> of the default -copy. Is there any way, to achieve that in Gnustep? 
> Shall we rewrite those classes to be compatible to that behaviour? I 
> mean it's usefull, but it's not object oriented in the case of Apple's 
> CoreFoundation library.

We don't implement CoreFoundation, but perhaps what you want to do is 
use NSMapTable ... that has the sort of functionality you are looking 
for.
NB. using retain rather than copy is dangerous, because a mutable 
object could change its hash... making it impossible to find/remove it 
from the collection in the normal way...  use with care.