Re: Re: [C++-sig] [Implementation] Calling wrapped functions, converters, policies

At 12:47 2003-09-21, David Abrahams wrote:
>Daniel Wallin <[email protected]> writes:
>
> > Does the converter really need access to the whole argument list? I
> > don't see why, at least if we do the "filtering" before passing it
> > into the converter function. I thought this is what you are doing in
> > Boost.Python with the new changes, but I could have misunderstood.
>
>Yes, that's what I'm doing, but it's not ideal.  For example, what
>gets passed to converters for out arguments that don't actually even
>appear in the XXX arguments?  What if you want a converter to combine
>two XXX arguments to produce one C++ argument?  These are the sorts of
>things that are possible with SWIG typemaps but not with Boost.Python.

Ok, that's kind of cool. So what you are suggesting is that the converter
gets the entire argument package, and the index?

   c0.convert(argument_package, mpl::int_<1>());

> >><snip>
> >>Anything I'm missing?  Your thoughts?
> >
> > No I think that about covers it. The current implementation (in
> > luabind, and some of langbinding..) doesn't use tag-dispatching for
> > the invoke functions, but I guess there are reasons that
> > tag-dispatch is better than class specialization here.
> >
> > BTW, does Boost.Python handle const functions/objects?
>
>There's no notion of const objects in Python, so although we do
>"handle" const member functions and objects, we don't do anything
>special for them.  There is a notion of immutability which applies to
>*types* (not objects), and I've thought about how that could be
>handled: http://mail.python.org/pipermail/c++-sig/2002-May/001023.html
>but haven't implemented anything.
>
> > In luabind we do
>
>What precisely do you mean by that?

I mean we preserve constness in the objects that are held in lua. We have
a bool in our object_rep that tells us if the object is const or not. This is
used in overload resolution.

---
Daniel Wallin



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