Re: New Ada portable GUI Library?

[Martin Krischik <krischik@users.sourceforge.net>]

Ludovic Brenta schrieb:
> Martin Krischik wrote:
>> Ludovic Brenta schrieb:
>>
>>> Martin Krischik wrote:
>>>> Ludovic Brenta schrieb:
>>>>
>>>>> Martin Krischik wrote:
>>>>>> I have another suggestion: A GUI Library based on OpenStep [1].
>>>>> [...]
>>>>>> [1] http://en.wikipedia.org/wiki/OpenStep
>>>>> Do you mean a reimplementation of the OpenStep specification in Ada,
>>>>> or an Ada binding to GNUstep (http://www.gnustep.org) ?
>>>> The later. AFAIK GNUStep uses only a small message based dynamically
>>>> typed API with a plain C specification. Qt and Gtk+ use huge OO API's in
>>>> C++ or some kind of strange OO-C.

> I agree that a static mapping doesn't make sense; that's why I was
> thinking about a binding generator. A preprocessor that takes Ada
> sources with directives and produces Ada sources wouldn't cut it
> because one would have to write the input files manually. The only
> sensible input is the Objective-C specification files.

I see what you mean - and probably we would need both. I might aim high
but I believe full integration should be the aim. And that means that
class B written in Objective-Ada inherits from Class A written in
Objective-C and Class C written in Objective-C++ inherits from Class B.

Now I believe neither GtkAda nor QtAda currently offer that kind of support.

>>> The stumbling blocks would be to implement Objective-C's reflection,
>>> dynamic typing and garbage collection in Ada. In particular,
>>> reflection and dynamic typing are alien to Ada's philosophy.

>> You don't - you use the objc runtime which should provide all those via
>>  plain C functions.

> No, because you must export callbacks from Ada so the Objective-C
> libraries can call them using dynamic typing and reflection. But Ada
> does not have dynamic typing or reflection. That's the problem.

Neither had C or C++ - that is all done by the (now build in) preprocessor.

>> But it will solve the biggest problem: the endless amount of methods. A
>> GUI lib easily got 100 classes. Defining 100 classes is doable - but
>> each class will have what about 20 methods. Yes 20 is realistic for GUI
>> lib. That would be 2000 pragma imports - endless work.
> 
> That's the job of the generator.

Yes - which might use reflection to get the data needed.

>>>>> would require both the Ada and Objective-C runtime libraries...
>>>> Indeed - but that is not different from Gtk+ and Qt approach. And bare
>>>> metal is only feasible for Windows but not for X11.
>>> OK, Qt requires a C++ runtime like GNUstep requires an Objective-C
>>> runtime. However, GTK+ only requires the C runtime
>> That might have been the original idea, but soon they needed Glib2 - to
>> make things easier. And then a few more: ATK, Cairo, Fontconfig,
>> FreeType, Pango, Poppler, libPNG, libXML, libiconv, librsvg, pkg-config
>> as of my last counting:
>>
>> http://gnuada.sourceforge.net/pmwiki.php/Main/PartnerProjects
> 
> But that is also true of the GNUstep libraries. They call them
> "frameworks" and there are several of them.

Yep. I guess all of them, Gtk+, Qt, GNUstep and indeed Win32 are
Runtimes of there own. Either we use one of those - or we create our
very own all in Ada - which brings us very quickly to AdaOS ;-) .

Martin
-- 
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Ada programming at: http://ada.krischik.com