Re: I want to understand (and new questions)

[Lars Hallberg <lah micropp se>]

On Wed, Apr 14, 1999 at 04:56:08PM +0900, Ionutz Borcoman wrote:
> Robert_Gasch/PeopleSoft@peoplesoft.com wrote:
> > 
> > 4) Using C++ as the base would make other language bindings more difficult
> > to write (??)
> C++ mangles names in the object code generated, while C not. I have
> understood that this is the reason why bindings to C code is simpler to
> made. Somebody please correct me if I'm wrong.

And the namemangling is not standarised so moduls from different compilers
might not link toghether - Thats a pain with 3:th party non sourcecode
librarys (but open source is a solution to that ;-).

Hovever, C++ have a keyword for declering C-functions so ther is no problem
to add an C interface to a C++ library. The data structurs is identical
(as long they ar *not* virual classes) so that ads no extra trouble.

The other way around, use a C library from C++ is also esy so the question
comes down to void ;-) With one exeption - callbacks and exeptions.

GTK is realy a framework that take (big) part of the controll of the
applikation and do callbacks to eventhandlers. That mens a C++ event
handlers can't throw an exeptions to be catched in an main C++ app.

If the event handler is defined in an library that might be anoying. I
guess it is anoying for some langage bindings to ;-)

What can be done?

1) Only use the low level GTK and write a new C++ framework.

   * Some stuff like confile interface and thems can hopfully be reused.

   * I have not looked at the source but i geuss the callbaks is
     raised from the widgets themself wich means all the widgets
     will be reimplemented :-(

2) Introduse an #ifdef branch that C++:ifies the GTK framework part

   * Advantage over abowe is that most parts of the widgets will
     be reused an that the two interfaces will follow eachother
     more naturly i the development.

   * Will slightly inkrease GTK owerall source complexity.

   * This will be a HUGE job but can be joint efort from GTK--,
     VDK and other C++ users. Thanks to CVS the efort shuld not
     need to come in the way for C developer (not much at least)

3) Live with an restricted usage of exeptions forewer :-(

Don't count on me for some while, I'm busy with glib C++ wraper and
face much the same troubles. Thats way ben thinking about it ;-)

So, i just wanted to share the ide. What do You C developers feel
about an C++ #ifdef branch for the 'framework' and othe callback
parts of GTK? It seams to be the 'less unreasnable' path for me
even if not compleatly reasnable ;-)

Thanks /Lars

PS Exeptions adds complexity the other way around to. You do
not want a C interface to a C++ lib to throw exeptions at an
helples C app :-( DS