Re: Bases 1.52

[Matthew Heaney <matthewjheaney@earthlink.net>]

Martin Krischik <krischik@users.sourceforge.net> writes:

> Yes, but to my knowlege you cant say:
> 
> type Item'Class is private;

This is all wrong.  If you have this generic formal type:

generic
   type T (<>) is private;
package GP is ...;

and this actual type:

package Q is
   type T is tagged private;
...
end Q;

Then you can instantiate the generic package like this:

package P is new GP (Q.T'Class);

The type T'Class is a real type.  It has a funny spelling, but it's a
real type.

You can declare objects of that type, both on the stack, like this:

  O : T'Class := ...;

and on the heap, like this:

  O : T_Class_Access := new T'Class'(Item);

You can write subprogram parameters --including function return types--
with that type.

And you can use T'Class as the generic actual type in a generic
instantiation.