From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.5-pre1 (2020-06-20) on
	ip-172-31-74-118.ec2.internal
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=3.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.5-pre1
Path: eternal-september.org!reader02.eternal-september.org!aioe.org!5WHqCw2XxjHb2npjM9GYbw.user.gioia.aioe.org.POSTED!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Simple example on interfaces
Date: Tue, 26 Jan 2021 12:53:19 +0100
Organization: Aioe.org NNTP Server
Message-ID: <ruovre$1sid$1@gioia.aioe.org>
References: <f44498d1-8675-44b2-af1e-3937dcbc7a1fn@googlegroups.com>
 <rumsck$nfj$1@gioia.aioe.org>
 <9e1b5d67-be08-4f53-aadc-fbed761a8c24n@googlegroups.com>
 <runfcf$1uub$1@gioia.aioe.org> <ruons9$ugr$1@dont-email.me>
 <ruoqn0$1cio$1@gioia.aioe.org>
 <e3f1af79-d957-4938-83fb-0f1c32a98444n@googlegroups.com>
NNTP-Posting-Host: 5WHqCw2XxjHb2npjM9GYbw.user.gioia.aioe.org
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Complaints-To: abuse@aioe.org
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101
 Thunderbird/78.6.1
X-Notice: Filtered by postfilter v. 0.9.2
Content-Language: en-US
Xref: reader02.eternal-september.org comp.lang.ada:61210
List-Id: <comp.lang.ada>

On 2021-01-26 12:15, AdaMagica wrote:
> Dmitry A. Kazakov schrieb am Dienstag, 26. Januar 2021 um 11:25:41 UTC+1:
>> How do I
>> spell in the language the fact that Long_Integer is an integer? If
>> Integer is an integer and Long_Integer is an integer can I write a
>> program that works on integers? Can it be the *same* program for each
>> instance of? Simple, natural questions.
> 
> This is what generics are for (since Ada 83).

Right, generics is a form of polymorphism (static one). Generics have 
interfaces and these form classes.

The problem with generics (static polymorphism which also includes 
overloading) is that they answer no to the last question. There cannot 
be same program because there is no class-wide (polymorphic) objects 
from the generics' class.

P.S. Comparing generics to overloading, generics offer some re-use, and 
some degree of formalization at the cost of producing huge mess, while 
overloading does none.

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