Re: tagged record child: override constructor?

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 14 Sep 2005 13:56:11 -0700, Hyman Rosen wrote:

> Dmitry A. Kazakov wrote:
>> There is no point in adopting what other languages did wrong.
> 
> Except that Ada isn't doing things any differently than the
> other languages, it's just adopted a notation that makes it
> confusing. Ada *does* allow redispatch, type tags *are* in
> every tagged object, you *can* convert from the type to the
> classwide type, tagged objects are *always* passed by
> reference.

Ada's model is the *only* model I know which allows:

1. A universal-purpose language (like C++ or Ada) to become a pure OO
language.

2. To support multiple dispatch

3. To avoid distributed overhead

4. To create a consistent construction/destruction model

OK, these opportunities weren't used, so what?

> But where C++ and Java will make dispatching
> calls where those are indicated by the class specification,
> Ada forces the programmer to request such calls in a strange
> way at call sites, and since there's nothing syntactically
> wrong with making a non-dispatching call, the programmer won't
> notice the mistake if that request isn't made.

Which mistake? Again, it is solely the actual object's *type* which
determines dispatch. It is 100% safe, intuitive and unambiguous. Ada is a
typed language! Is C++ one?

>> As I said before, it is equivalent to dispatch that does not happen.
> 
> You may say it all you like, but my code clearly demonstrates
> that dispatching *does* happen. B::B() calls A::g()

No. It calls B::g() which was inherited from A. I don't care if code of
B::g() and A::g() share memory or not. They are different functions because
their signatures are different.

> and that dispatches to B::f().

It does not. It calls B::f() from B::g()

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de