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From: tardieu@valjean.enst.fr (Samuel Tardieu)
Newsgroups: comp.lang.ada
Subject: Re: How to dynamically dispatch?
Date: 17 Mar 1995 11:37:56 +0100
Organization: TELECOM Paris
Message-ID: <tardieuzngjzcilnqam@valjean.enst.fr>
References: <3k8m9f$eci@goanna.cs.rmit.edu.au>
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To: Dale Stanbrough <dale@rmit.edu.au>
In-reply-to: Dale Stanbrough's message of 16 Mar 1995 06:36:31 GMT
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Date: 1995-03-17T11:37:56+01:00
List-Id: <comp.lang.ada>

GNAT has no way to know that there is an 'eval' function defined for
any object of type Expression'Class, it only knows that there is one
for 'literal' and 'binary_operation' types.

You may want to add an abstract function to type Expression to force
developpers to add this function to any new type they create from
Expression and let GNAT know that such a fonction exists:

function Eval (Item : Expression) return Integer is abstract;

Hope this helps.

  Sam

-- 
"La cervelle des petits enfants, ca doit avoir comme un petit gout de noisette"
                                                       Charles Baudelaire