[C++-sig] Overloaded pure virtual method

[Roman Yakovenko]

On 10/24/06, Mark Williams <mark at image-engine.com> wrote:
>
> Hi, I'm having some difficulty understanding the syntax for binding pure virtual member functions with default arguments. Here
> is a simple class definition:
>
> class TestOverloads
> {
>         public:
>                 virtual ~TestOverloads() {}
>                 virtual void overloaded(float f = 0) =0;
>
> };
>
> I have also defined:
>
> BOOST_PYTHON_MEMBER_FUNCTION_OVERLOADS(MyOverloads, overloaded, 0, 1);

This macro should not be used for pure virtual functions.

> What am I doing wrong here, please?

You should use boost::python::arg to add default value.

http://boost.org/libs/python/doc/v2/args.html

Next code was generated by Py++:

struct TestOverloads_wrapper : TestOverloads, bp::wrapper< TestOverloads > {

    TestOverloads_wrapper()
    : TestOverloads()
      , bp::wrapper< TestOverloads >(){
        // null constructor

    }

    virtual void overloaded( float f=0 ){
        bp::override func_overloaded = this->get_override( "overloaded" );
        func_overloaded( f );
    }

};

BOOST_PYTHON_MODULE(pyplusplus){
    bp::class_< TestOverloads_wrapper, boost::noncopyable >(
"TestOverloads" )
        .def(
            "overloaded"
            , bp::pure_virtual( &::TestOverloads::overloaded )
            , ( bp::arg("f")=0 ) );
}

This code allows you to create new classes in Python that derives from
TestOverloads class.

-- 
Roman Yakovenko
C++ Python language binding
http://www.language-binding.net/