From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,d1ced5efd53fe6a1
X-Google-Attributes: gid103376,public
From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: Can Ada95 interface with C++?
Date: 1997/02/24
Message-ID: <dewar.856787229@merv>#1/1
X-Deja-AN: 221056628
References: <5csvbd$ia2@top.mitre.org> <32F60684.59E2@gslink.net>
 <32F94DD7.3F54BC7E@worldnet.att.net> <1997Feb6.150722.14570@ocsystems.com>
 <1997Feb6.130819.1@eisner> <dewar.855276105@merv>
 <tx1bu9rp8sr.fsf@cygnus.com> <1997Feb11.153355.1@eisner>
 <1997Feb12.004642.31821@ocsystems.com>
Organization: New York University
Newsgroups: comp.lang.ada
Date: 1997-02-24T00:00:00+00:00
List-Id: <comp.lang.ada>


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.