Re: Ada Annoyances

[Maciej Sobczak <see.my.homepage@gmail.com>]

> For T substitute Abstract_TCP_Server. For Bar substitute 
> Get_IP_Address_To_Listen.

And I still don't see any benefit. Can you explain what functionality is available in this scheme (and that is not available currently in Ada or C++)?

> > Wrong.
> > C++ does not kill any dispatching anywhere. Calls to virtual functions from constructors/destructors are dispatching.
> 
> That is just same plus heating of the environment.

You are running out of arguments.
Calls to virtual functions while the object is during construction need to work like usual, because they need not be done from the constructor:

void useObject(Base & obj)
{
    obj.foo(); // dispatching call to foo()
}

Base::Base()
{
    // some initialization ...

    useObject(*this);
}

Derived::Derived()
{
    // some initialization ...

    useObject(*this);
}


The useObject function does not know what it gets as an argument and we want it to dispatch to the most specific part, but surely we do not want it to dispatch to the parts that do not yet exist. Most importantly, useObject does not know that it gets called from constructors, because it might be called from any other context as well. It might be even in a different translation unit.

This shows that dispatching is *not* "killed" and whatever environment heating takes place, it is needed, like in any other place where dispatching is considered useful. We can discuss the useless environment heating imposed by Controlled in Ada, instead.

I understand that it is beyond the threshold of humiliation for a die-hard Ada programmer, but I personally don't find it difficult to admit that this is the part that C++ got right.

-- 
Maciej Sobczak * http://www.inspirel.com