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From: dvdeug@x8b4e53cd. (David Starner)
Subject: Re: Ada95 Strengths/Weaknesses.
Date: 1999/09/28
Message-ID: <7splaj$7pu1@news.cis.okstate.edu>#1/1
X-Deja-AN: 530192170
References: <37EED7B8.245C0054@yukyonline.co.yuky>
 <7smp30$9aa1@news.cis.okstate.edu> <7sp914$ago$1@nnrp1.deja.com>
Organization: Oklahoma State University
User-Agent: slrn/0.9.5.7 (UNIX)
Reply-To: dstarner98@aasaa.ofe.org
Newsgroups: comp.lang.ada
Date: 1999-09-28T00:00:00+00:00
List-Id: <comp.lang.ada>

In article <7sp914$ago$1@nnrp1.deja.com>, Robert Dewar wrote:
>In article <7smp30$9aa1@news.cis.okstate.edu>,
>> * C++ includes several somewhat experimental features
>> (template specilization,
>> multiple inheritance) that Ada designers considered too
>> experimental or
>> specialized to add.
>
>Well I think you need to give examples here. Many people would
>regard the multiple inheritance in C++ to be a disadvantage for
>three reasons:
>
>1. The OO model is much cleaner if only single inheritance is
>used, so the semantics is much simpler. This is why many OO
>languages deliberately avoid supporting MI.
>
>2. The MI model in C++ is one of several. Having a specific
>model built into the language is unhelpful if your problem is
>best handled by some different model.
>
>3. In most C++ compilers, you pay a price in distributed
>overhead for this feature, even if you do not use multiple
>inheritance.

A clearer way to express my objections to your objections here is:
you're viewing from the point of view of a language & compiler 
designer. From a programmer's standpoint, multiple inheritance
can be a useful tool. And hence, to them, it is a disadvantage
that you don't have MI in Ada.

One minor problem in Ada that MI could help is the special
Controlled classes. Either your base class is derived from
it, or it isn't and that limits your subclasses. There's no
way in Ada to add another 'special' base class without providing
it Controlled and Uncontrolled versions, or something otherwise
ugly or arbitrary.

David Starner - dstarner98@aasaa.ofe.org