Re: JGNAT and Null references

["Marc A. Criley" <mcqnet@earthlink.net>]

Randy Brukardt wrote:
> 
> Marc A. Criley wrote in message <3AA151BF.C9193700@earthlink.net>...
> >Uh...it did work.  Cleared up the problem just fine.  That it works
> >doesn't totally sit well with me, since my purist mental picture of a
> >"constant" involves only a value, and not storage.  Nonetheless,
> >
> >   Null_Icon : constant Javax.swing.TabbedPanel.ref := null;
> >
> >was accepted by the AddTab procedure call.
> 
> But does it run? The RM  4.6(49) says that an access parameter cannot be
> null, and must raise Constraint_Error. If it does run, you're using a
> compiler bug (or "feature"); your code won't be portable...
> 
>         Randy.

Oh yes, it does run.

As I'm not a supported user of JGNAT, having access only to the public
1.1p version, I can't ask ACT about this.

My question, though, would be: If an access parameter cannot be null,
how am I supposed to pass a null argument to a Java method, given the
way jvm2ada generates the Ada binding?  Is the present behavior a bug? 
Is it a JGNAT-specific extension that perhaps ought to be wrapped in the
Extensions_Allowed behavior?

As for portability, unless there's a standard approach for defining Ada
bindings to Java classes and methods, I suspect I'm strongly wrapped up
in JGNAT-specificity anyways.

Marc