Re: Ada 0y wish list: "with private"

[Keith Thompson <kst@cts.com>]

"Thierry Lelegard" <thierry.lelegard@canal-plus.fr> writes:
> Recently, several wishlist items for Ada 0y were posted in c.l.a.
> Like many old Ada users, I have a couple of them. I would like to
> propose one for discussion: a "with private" extension.
> 
> The idea is to specify in a context clause of a unit spec that an
> external unit can be used only in the private part.
> 
> Example:
> 
> with A;
> with private B;
> package C is
>    X : A.TA;
> private
>    Y : B.TB; -- legal only in private part
> end C;

What about this syntax:

with A;
package C is
   X : A.TA;
private
   with B;
   Y : B.TB;
end C;

The advantage is that it puts the context clause within the private
part, which is what it applies to.

One possible drawback: Currently, the compiler sees all the context
clauses before the beginning of the package; with this syntax, it will
have to process the public declarations of C before seeing the "with
B;".  Some implementations would have more difficulty with this than
others; would it be an unreasonable burden for any of them?

(It also looks a bit odd to put a context clause into a sequence of
declarations.)

-- 
Keith Thompson (The_Other_Keith) kst@cts.com  <http://www.ghoti.net/~kst>
San Diego Supercomputer Center           <*>  <http://www.sdsc.edu/~kst>
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