Re: Generic units and child units

[Robert A Duff <bobduff@world.std.com>]

Brian Rogoff <bpr@shell5.ba.best.com> writes:

> > generic
> >    type Item is private;
> > package List is
> >     ... blah blah
> > end List;
> > 
> > generic
> > package List.Iterator is
> >    ... blah blah
> > end List.Iterator;
> 
> That's right, all children of a generic package must be generic. 
> > 
> > 
> > In my test program I can instantiate a List for integers:
> > 
> > with List;
> > procedure Test is
> >     package Integer_List is new List (Item => Integer);
> 
>       package Integer_List_Iterator is new Integer_List.Iterator;
> 
> is the correct syntax.

Right, but don't forget to say "with List.Iterator;".  When you
instantiate List to create Integer_List, it's as if you were
instantiating the whole hierarchy of children, except that the children
of Integer_List are not visible unless the corresponding children of
List are with'ed.  That is, "with List.Iterator;" causes
Integer_List.Iterator to be visible, so you can then instantiate it.

This is all sort of theoretical -- in practise, the compiler will
typically just instantiate the children it needs to; it typically
doesn't even know about the whole hierarchy, because new children can be
added later.

See RM-10.1.1 and 8.3(20).

- Bob
-- 
Change robert to bob to get my real email address.  Sorry.