Re: Extension of non-limited type needs limited component

["Jean-Pierre Rosen" <rosen@adalog.fr>]

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"Mike" <michael.jackson5@virgin.net> a �crit dans le message news:
2dbd76f3.0211140126.5d233e41@posting.google.com...
> How can assignment by upcasting the extended type possibly affect the
> limited component?
>
Consider:

   X : T'class := Some_Dynamic_Function (1);
   Y : T'class := Some_Dynamic_Function (2);
begin
   X := Y;

At compile time, we know nothing about the specific type of the values in X
and Y, but assuming that T is not limited, the assignment is allowed. If X
and Y happen to have different tags at run time, the assignment will raise
Constraint_Error, but that's all.

If you were allowed to extend T with limited components, you would
effectively copy the limited components!

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           J-P. Rosen (rosen@adalog.fr)
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