Re: Can Ada95 interface with C++?

[dewar@merv.cs.nyu.edu (Robert Dewar)]

Joel says

<<For example, C++ classes without virtual functions are called
"nonpolymorphic" classes.  There is no such thing in Ada95 because a
a CALL to a primitive op of a tagged type in Ada95 is what determines
whether the call dispatches, not the declaration of the operation.  Another
big problem is the different way initialization/finalization is handled.
None of this even touches upon MI (ack)>>


There is no problem in defining the equivalent of nonpolymorphic classes.
To define "methods" in Ada 95 that are not virtual (using the C++
terminology), just don't make them primitive. Then they can be applied
to any member of the class (the formal type is x'class in this case).

It *is* the declaration of the operation in Ada 95 that determines whether
the call dispatches. A class wide operation never dispatches. So the first
concern here just seems plain wrong.

I do not see why initialization/finalization is a big problem either. The
GNAT interface design provides a clean way of interfacing to constructors
and destructors (though this is not fuly implemented yet).

Finally, the GNAT design handles multiply inherited classes without a
problem. You cannot *define* such a class within Ada, but you can
certainly *import* such a class.