Re: objective-c: how slow ?

[Erik M. Buck]

> I admit I don't know in detail the lookup mechanism in the objc runtime
> but I suppose that rebuilding the sarray after a inheritance change would
be
> very expensive. Multiple inheritance requres a resoulution when the same

As long as the instance variable layout does not change, dynamically
changing the super class of an existing class is one pointer operation.
Each class object has a "superclass" variable.  The message cache tables are
per-class (At least in my runtime and Apple's runtime) so changing a
superclass automatically changes the method cache with no extra effort.