Re: Extension of non-limited type needs limited component

[Robert A Duff <bobduff@shell01.TheWorld.com>]

michael.jackson5@virgin.net (Mike) writes:

> How can assignment by upcasting the extended type possibly affect the
> limited component?

If you have "type T2 is new T1 with...", then it is important that if T2
is limited, then T1'Class must also be limited, because ":=" on T1'Class
objects will copy the T2 part, if the objects' tag happens to be T2'Tag.

In Ada, T1'Class is limited if and only if T1 is limited.
So that means the whole hierarchy of tagged types has to be
either limited or nonlimited.  I'm not sure if it would cause semantic
troubles to allow a nonlimited T1 with a limited T1'Class (assuming one
could invent some syntax for saying so).  Interesting question.

- Bob