[C++-sig] Re: Boost.Python : Byref parameters - no problems with static/non-static overloading

[Joel Gerard]

Ok.  I've got things mostly sorted out.  You can't overload static and non-static member
functions, which is fine, but how do you use a static (not overloaded) function in Python? I need
to keep the static function in the class scope. The reason is name collision, i.e.

class A
{
   static void foo();
}

class B 
{
   static void foo();
}

I have:
class Vector
{
public:
    static  void        Orthonormalize          (Vector& kU, Vector& kV, Vector& kW);
}

Wrapped as:


void (*Orthonormalize2)(Vector&, Vector&, Vector&)      = &Vector::Orthonormalize;
.def("Orthonormalize",Orthonormalize2)
            .staticmethod("Orthonormalize")

In python, do you just use it as an unbound method?  Is the self argument non-existent in this
case, or do I do something different?

Currently I have:
Vector.Orthonormalize (Vector1, Vector2, Vector3)

Also, is there a good place to look for python examples. I didn't see a python example in the
docs, but perhaps there is something else? 

Thanks,
Joel

--- David Abrahams <> wrote:
> Joel Gerard <> writes:
> 
> > Thanks for the advice. There are a few things I'm still vague on though. I've been overloading
> > static, and non-static members without apparent problems, but I'm now starting to be
> suspicious. 
> >
> > For instance, I have: 
> >
> > Vector (Vector::*CreateCross1)(const Vector&) const  = &Vector::CreateCross ;
> > Vector (*CreateCross2)(const Vector&, const Vector&) = &Vector::CreateCross; 
> >
> > .def("CreateCross",CreateCross1)
> > .def("CreateCross",CreateCross2)
> >
> > The one I call as a bound method, and the other unbound, i.e.:
> >
> > Vector2 = Vector1.CreateCross(Vector3)
> > Vector2 = module.Vector.CreateCross(Vector1,Vector3)
> >
> > Is something going on here that I'm not seeing. They work ok apparently.
> 
> Both are calling CreateCross2.
> 
> > Regarding the vector problem. I cannot modify the original C++ code.  I want to keep Normalize
> as
> > an unbound method in Vector since I might have name collisions if I
> > put them at the module level. 
> 
> What collisions?  There's overloading at the module level too, you
> know.
> 
> > I tried .def("Yahoo",Normalize3) but it too gave me a type
> > error. What is Boost trying to do? 
> 
> I have no idea; post a reproducible test case.
> 
> Maybe you forgot to make it static?
> 
> > The function pointer is poiting to the correct function.
> >
> > Furthermore, don't you have to do something different than just a
> > plain .def since the arguments to Normalize are references? 
> 
> No.
> 
> > Does Boost automatically detect this?
> 
> It does detect that they are references.
> 
> > How does it deal with something like:
> >
> > Add(int x, int y, int &result)
> >
> > So when you do >>>Add(x,y,result) in python, what happens?
> 
> argument error, but that's because Python ints are immutable.  Classes
> don't play by the same rules.
> 
> > I think I'm missing something fundamental here... :(
> >
> > Thanks for your help.
> > Joel
> 
> Sure thing.
> 
> -- 
> Dave Abrahams
> Boost Consulting
> www.boost-consulting.com
> 
> 
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=====
--------------------------------------
Email: joelgerard at canada.com

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