Re: Ada Distilled by Richard Riehle

[Vincent <vincent.diemunsch@gmail.com>]

Le samedi 28 juillet 2018 17:41:53 UTC+2, Dmitry A. Kazakov a écrit :
 
> Ada 95 never had methods nested in type declaration. (Ada 83 did this 
> error for protected objects and tasks, but the lesson was learned)

What is the problem with methods nested in type declaration ?

It seems to me that with the Ada95 OO style, we have awful "freezing rules", and less visibility of which operation is dispatching and which is not.

> Yes, Ada's OO model is the only correct one, IMO. 
> The concept of operations nested class type declaration is evident garbage in the light of MD. 

But that's a paradox since as you mentioned, this Ada model is not able to deal with MD !

In both cases (in Ada and in languages that nest methods in types) one needs to deal with multiple dispatch "at hand" by an ad hoc procedure that uses class wide arguments and test them. For the obvious reason that there is no evident ordering of a pair of elements, event if each element is ordered.

Regards,

Vincent