Re: Bizarre JGNAT things

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

Andrzej Lewandowski wrote:
> 
> <gary_the_fox@richmond.com> wrote in message news:9a5kqt$cnu$1@news.netmar.com...
> > Hello!
>  > The most bizarre thing is that happens to two files only -
> > com-sun-java-swing-plaf-motif-MotifLookAndFeel.ads and
> > com-sun-java-swing-plaf-windows-WindowsLookAndFeel.ads. All other files,
> > including ones with almost identical structure, compile OK, in the same
> > directory, with the same settings. The extremely similar
> > javax-swing-plaf-metal-MetalLookAndFeel.ads compiles OK also.
> >
> > Do I do anything wrong?
> >
> 
> Yes. Wrong is that you are using JGNAT. I gave up after many
> attempts.
> 

Curious.

I've got tables, trees, pop up menus, socket communications, and so on,
all written using JGNAT and working quite nicely.  Granted, I would like
to see a a post-1.1p release that hopefully smoothed some of the
product's rough edges, but I find it quite usable.

There's one critical aspect of JGNAT that a prospective user _must_
understand.  If one tries to write code with JGNAT using the same
"style" one does when writing typical Ada programs, that will likely
work only if you're writing "isolated" code, meaning, little or no
interaction with the JDK class library.

If you're going to interface to JDK classes, as I've been doing, one
must understand _and_conform_ (at least to some extent) with the Java
approach.  The JDK is heavily based on inheritance and implementing
interfaces, therefore your JGNAT compiled Ada code also has to employ
inheritance and polymorphism much more than is typically required of Ada
programs.

My approach has been to write the core code using the standard Ada
idioms, and then adapting to the Java way around the fringes.  This is
in contrast to writing all the code in a Java idiom, and employing "with
type" and coding up my own interfaces and such.  I just leave that
latter stuff to jvm2ada.

Marc A. Criley