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From: Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov>
Newsgroups: comp.lang.ada
Subject: Re: Generic default parameters
Date: 13 May 2002 10:00:26 -0400
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Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> writes:

> 6. A more liberal matching of actual subprograms against formal ones.
> If some parameters of the actual subrogram have defaults, then they
> can be absent in the formal one.
> 
> generic
>    with procedure Put (Item  : in Object) is <>;
> package Foo ...
> 
> Then an instantiation with Integer_IO.Put:
> 
> procedure Put
> (  Item  : in Num;
>    Width : in Field := Default_Width;
>    Base  : in Number_Base := Default_Base
> );
> 
> should be legal.

I like this. I don't see how it could be a problem.

> 7. Incomplete instantiations:
> 
>    package X is new Y (<>);
>    --
>    -- No actual parameters given.
>    -- All declarations of the visible part of X
>    -- are incomplete here in usual sense.
>    -- I.e. if X declares a a type XX then
>    --    type XX_Ptr is access X.XX;
>    -- would be OK.
> . . .
> private
>    package X is new Y (<parameter-list>);
> 
> The formal parameters which actuals are not visible in the public
> part, shall be only used in the private part or the body of the
> generic. The idea is to instantiate a generic with some private things
> and yet to have the instance visible.

This I'm less happy with. I think you can get the same effect with
library instantiations and/or child packages.

-- 
-- Stephe