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From: Fraser Wilson <newsfraser@blancolioni.org>
Newsgroups: comp.lang.ada
Subject: Re: Announce: Grace project site operational
Date: 17 May 2002 18:09:53 +0200
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Date: 2002-05-17T16:08:34+00:00
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Mark Biggar <mark.a.biggar@attbi.com> writes:

> No, your problem is not with Standard."*", it is with the implicit
> definition of 'function "*"(Left, Right: Metres) return Metres' that
> you get when you defined the type Metres.

My bad; sloppy terminology.

> Ada 95 provides a way to
> turn off such implicit definitions like so:
> 
> type Metres is new Float;
> -- kill unwanted ops
> function "*"(Left, Right: Metres) return Metres is abstract;
> function "/"(Left, Right: Meters) return Metres is abstract;
> -- define wanted ops
> function "*"(Left, Right: Metres) return Area;
> function "*"(Left: Float, Right: Metres) return Metres;

This doesn't resolve the ambiguity of

   X : Metres;
   X := 2.0 * X;

... it just prevents you from compiling a program that makes an 
unambiguous call to the unwanted operations.

Fraser.