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From: Florian Weimer <fw@deneb.enyo.de>
Newsgroups: comp.lang.ada
Subject: Re: on package naming, should the word
Date: Mon, 15 Oct 2001 23:17:17 +0200
Organization: Enyo's not your organization
Message-ID: <87u1x0a9ia.fsf@deneb.enyo.de>
References: <mailman.1002721517.7620.comp.lang.ada@ada.eu.org>
 <9q25ec0248o@drn.newsguy.com>
 <slrn9sanqm.cb.randhol+abuse@kiuk0156.chembio.ntnu.no>
 <9q421v0bbg@drn.newsguy.com> <mlhx7.24432$ev2.32999@www.newsranger.com>
 <9q4d850163k@drn.newsguy.com> <3BC9F6CC.E41BE18A@nbi.dk>
 <9qd2340djj@drn.newsguy.com> <slrn9slk5q.i2.lutz@taranis.iks-jena.de>
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Date: 2001-10-15T23:17:17+02:00
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lutz@iks-jena.de (Lutz Donnerhacke) writes:

> * Robert*@ wrote:
> >In article <3BC9F6CC.E41BE18A@nbi.dk>, Jacob says...
>>>The object prefix notation has a very serious limitation,
>>>which would actually break quite a few of my programs. Using
>>>the object prefix notation, it is not possible to dispatch
>>>on the function result type.
>>
>>A simple example of what you mean? 
>
>   type Error is tagged abstract private;
>   procedure Alarm (e : Error) is abstract;
>   function Current_Error returns Error'Class;
> ...
>   Alarm (Current_Error);

Python translation, in prefix notation:

    class Error:
        def Alarm(self):
            pass
    
    def Current_Error():
        ...
        return <something>
    
    Current_Error().Alarm()

In your example, Current_Error is clearly non-dispatching, so this is
not an example for dispatching on the function result type.

By the way, C++ does indeed offer static dispatching on the function
return type, but the last time I tried it, it involved a considerable
syntactic overhead.