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From: Robert A Duff <bobduff@shell01.TheWorld.com>
Newsgroups: comp.lang.ada
Subject: Re: Saturated Math
Date: 28 May 2003 16:06:15 -0400
Organization: The World Public Access UNIX, Brookline, MA
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Date: 2003-05-28T16:06:15-04:00
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"Randy Brukardt" <randy@rrsoftware.com> writes:

> Something like:
> 
>         package Saturation is
>             type Saturated_Integer is private;
>             for Saturated_Integer'Literal use Convert;
>             function Convert (Value : in Root_Integer) return
> Saturated_Integer;
> 
>             function "+" (Left, Right : Saturated_Integer) return
> Saturated_Integer;
>             -- etc.
>       end Saturation;
> 
> The idea being that when a literal occurs, the compiler wraps it into a
> call to Convert. You can sort of do this with unary "+", but it's
> annoying to always have to write "+" (and you also don't have a named
> "Root_Integer" type to use, so you have to use some other Integer type
> to get the proper range).
> 
> There hasn't been much interest in this idea (or the related
> redefinition of array indexing), so don't hold your breath waiting for
> it.

I've always thought this sort of thing was a good idea.

But I think the 'Literal attribute should take a String.
That's what a literal is -- a string in the source code,
which the compiler converts into a value.  The goal is to give
the user a hook to control that conversion.

A good compiler could run Convert at compile time in most cases.

- Bob