Re: Message negociation

Artem Baguinski wrote:

> the vtables with NULLs for not-implemented "methods" will be even more
> efficient, cause you request all callbacks at once ;)

Nop, that's not the same thing. If you request everything at once, that 
means you know the order of things in the vtable, ie using a fixed 
struct. Hopefully the impact of using a struct is less important than 
"message" parameters. You can add new callbacks at the end. Hopefully we 
will never have a system with 5000 callbacks/message :) (and even though 
it can still be handled by mosts systems)

So I agree with the vtable requested on "init". Something that would 
look like this :

typedef struct dialog_vtable {
	int (*callback1)(void);
	void (*callback2)(int);
	long (*callback3)(long, void *);
	....
};

int get_your_vtable(dialog_vtable *table_to_fill, int size_of_this_table);

Depending on the "size_of_this_table" you know when to stop filling the 
structure (or fill it with NULL when you support less features).

As said before, the structure has to be updated at the end, *always*.