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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Ada 83 - avoiding unchecked conversions.
Date: 1996/12/14
Message-ID: <E2FDt4.G30@world.std.com>#1/1
X-Deja-AN: 204164096
references: <md5:8B831999BCF200C6E70994BDF6CC529F>
 <mheaney-ya023280001112962007210001@news.ni.net>
 <32B062D3.7E9A@ccgate.hac.com> <32B17F46.123B@gsfc.nasa.gov>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: comp.lang.ada
Date: 1996-12-14T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <32B17F46.123B@gsfc.nasa.gov>,
Stephen Leake  <Stephen.Leake@gsfc.nasa.gov> wrote:
>Perhaps there should have been a type "Fast_Integer", with the
>understanding that it was at least 16 bits (this is of course just
>Standard.Integer). Then programmers can use Fast_Integer when they don't
>really care about the size.

Sometimes, you want "an integer of at least so-and-so range, but I don't
mind if it has more range, so long as it doesn't cost me any
efficiency".  To say that in Ada 95:

    type Specific_Range is range -10_000..10_000;
    subtype T is Specific_Range'Base;

Then use T all over.

Other times, you want an integer type that has something to do with the
amount of addressable memory on the machine.  E.g. type String, where
the index type is Integer, and one presumes that Integer is 16 bits on a
16-bit machine, and 32 bits on a 32-bit machine -- that makes sense,
since you won't want to create 10 megabyte strings on the 16-bit
machine, but you might on the 32-bit machine.

- Bob