Re: use of attribute Pos

[Robert A Duff <bobduff@world.std.com>]

Philippe Torres <ptorres@laas.fr> writes:

> type Upper is new Character range 'A'..'Z' ;

> Since a different type is introduced, how does Pos still refer to
> Character ?

Because the *type* contains all those 256 characters.
The above is essentially equivalent to:

    type Mumble is new Character;
    subtype Upper is Mumble range 'A'..'Z';

So, for example, you could say:

    X: Upper'Base := '+'; -- Upper'Base is the base (unconstrained) subtype.
    Y: Upper := Upper'Succ('@'); -- Initializes Y to 'A'.

In other words, '+' and '@' are values of the type, even though Upper is
constrained not to include them.

- Bob