Jon Smirl,
I took the liberty of CC'ing the lists again as it is a very valid point
you make here.
On Mon, Mar 10, 2003 at 03:17:56PM -0800, Jon Smirl wrote:
> --- José Fonseca <[EMAIL PROTECTED]>
> wrote:
> > On Mon, Mar 10, 2003 at 10:36:21PM +0000, Keith
> > Whitwell wrote:
> > > No, because one of the things C++ does is pass
> > around an extra parameter --
> > > namely the 'self' pointer. The 'real' prototype
> > looks something like:
> > >
> > > void Context::BlendFunc( Context *self, GLenum
> > sfactor, GLenum
> > > dfactor )
> >
> > I know this, that's why I thought there could be a
> > remote chance to make
> > it work, as the arguments mostly match, i.e., ctx =
> > self.
> >
>
> I wasn't really paying attention to this, but don't
> you just want to do this, compiled with c++....
>
> _cdecl handler(Context* self, sfactor, dfactor)
> {
> self->(sfactor, dfactor);
> }
>
> _cdecl will export the function as an non-name mangled
> C entry point. _cdecl is from windows, I don't know
> what the g++ equivalent is. You can probably inline
> this and make it completely go away when compiled.
Yes, this works as you say _if_ the method isn't virtual, or at least
the exact type of the class is known at compile time, i.e., it's not an
abstract Context *, but actually a non-abstract RadeonContext *.
Unfortunately most interesting cases, you desired that method to be
virtual. This means that if you really want to eliminate the call you
need to write a different "_cdecl handler" for each of the inherited
classes and update the function table in run-time. Or at least use a
template to write all of them for you.
I've never though of this [and e.g. all mesa wrappers so far have that
extra redirection call], until Keith said that this [of updating the
funcion table in run-time] was something he desired to use more
extensively.
Nevertheless, this solution will require the extensive use of templates
and it won't be pretty, so I'll leave it to when the framework
stabilizes.
José Fonseca
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