Re: Elemantary Ada question

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

reinert@ola.npolar.no (Reinert Korsnes) writes:

> Can anybody explain me why "A : Float" conflicts
> with the declaration:  "type E1 is (a, b, c);" ?

Enumeration literals are overloadable, but variables are not
overloadable.  You are not allowed to have a non-overloadable A if there
is some other A in the same scope (even if the other one is
overloadable).

The exact rules are in chapter 8 of the RM.  It says that two
declarations with the same name are "homographs" if one or both are
non-overloadable.  Also, if both are overloadable, and have the same
parameter and result types (where the enumeration literal A is like a
parameterless function returning type E1).  It is illegal to have two
homographs in the same "declarative region".

Or perhaps you are asking why was the language defined that way.
Well, variable names could be overloadable, and the language rules
would work just fine.  The above would be legal, and things like

    X: E1 := A;

would resolve to the right A.  Things like "if A = A..." would be
ambiguous, and therefore illegal.

- Bob