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From: Mats Weber <Mats.Weber@elca-matrix.ch>
Subject: Re: Question about base types
Date: 1997/02/10
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Date: 1997-02-10T00:00:00+00:00
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> Mats, you are confused, the base type (and hence the range of intermediate
> results) is always unconstrained, so that if you write:
> 
>    subtype Real is digits 7 range 0.0 .. 1.0;

should type instead of subtype, right ?

> as in the original result, you will still get an unconstrained 7 digit
> base type.

So you are saying that

   type Real is digits 7 range 0.0 .. 1.0;   -- (1)

and 

   type Real_Base is digits 7;
   subtype Real is Real_Base range 0.0 .. 1.0;   -- (2)

are equivalent except for the existence of the name Real_Base ?

Well that's not what I get from reading RM 3.5.7(10). In the first case,
I get a safe (and base) range of at least -1.0 .. 1.0, and in the
second,
- 10.0 ** 28 .. 10.0 ** 28.

Now I know that this is not true for any reasonable implementation
because floating point base types are always created from a finite set
of representations available on the machine, but according to the RM
there could exist a legal implementation of Ada 95 for which 100.0 is a
possible value of Real'Base in variant (2) but not in variant (1). Or am
I missing soemthing ? (If I am, then the RM is confusing).