Re: Supertypes RE: Extensible Enumerated types

[Marin David Condic <mcondic.auntie.spam@acm.org>]

I could see that as interesting - sort of building onto type extension. There
may be issues with representation that need to be looked at, do you think? I
guess my only reservation would be that it needs to be asked how generally
useful is this? Would it enable some significant new technique that would get
used often enough to make it worth disturbing the reserved word list?

MDC

Robert C. Leif, Ph.D. wrote:

> From: Bob Leif
> To: My fellow Ada users
>
> This is suggestion includes the addition of a new keyword to Ada. I realize
> that some would consider this rank heresy.
>
> Since Ada has Subtypes to specify a subset of a type, it would be reasonable
> to create a symmetrical operation to create a superset of a type.
>
> -- from Package Prefix_Recs
> type Prefix_Type is (None, Mr, Ms, Miss, Mrs, Dr, Prof, Rev,
>     Other);
>
> --From Package Prefix_Recs.Army
> Supertype Army_Prefix_Type is (Prefix_Type, Private, Corporal, Sergeant,
> Lieutenant, Captain, Major, Colonel, General);
>
> Prefix_Type'range would also be a possibility.
>
> Army_Prefix_Type would inherit all of the operations of Prefix_Type.
>
> I believe that super is lexicography a better choice than supra. I must add
> that supertypes are appropriate for a super language.

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