Re: using an Ada.Container as a private type

Graham <graham.stark@[EMAIL PROTECTED]
> writes:

>    type Payment_Stream is new Payment_Stream_Package.Map;
>
> but I can't do this. Gnat complains that "type derived from tagged
> type must have extension".
> I'm fairly new to Ada but thought I was getting on top of it! What is
> the principal that stops me doing this? What should I do instead?

Not really a "principle" -- more like an arbitrary restriction.
Map is tagged, and tagged types have to obey that rule.

You should say:

    type Payment_Stream is new Payment_Stream_Package.Map
        with null record;

to create an empty extension.

- Bob