当我想使用Swig％extend扩展给定类时出现Swig问题

Question

I have this following code in my Swig file (.i) :

%extend vgSofa::handler::VertexShape
{

        vgd::Shp< vgSofa::handler::VertexShape > createVSWithNode( sofa::simulation::Node * root )
        {
            vgd::Shp< vgSofa::handler::VertexShape > result( new vgSofa::handler::VertexShape() );

            return result->init(root) ? result : vgd::Shp< vgSofa::handler::VertexShape >();
        }           

        vgd::Shp< vgSofa::handler::VertexShape > createVSWithBsicHandler( vgd::Shp<vgSofa::handler::BasicHandler> h )
        {
            return vgSofa_handler_VertexShape_createVSWithNode( $self, h->getRoot() );
        }   


};

in .cpp file created, swig adds another parameter in my methods :

SWIGINTERN vgd::Shp< vgSofa::handler::VertexShape > vgSofa_handler_VertexShape_createVSWithBsicHandler(vgSofa::handler::VertexShape *self,vgd::Shp< vgSofa::handler::BasicHandler > h)
{...}

How do I prevent the addition of this additional parameter to VertexShape?

Answer 1

That is a normal behavior. SWIG's %extend directive generates stand-alone functions in the generated code. If you use $self in the body, that function is provided with an argument (named "self") that is a pointer to an instance of the C++ class.

As a side note: C++ does the same thing under the hood. The this pointer is implicitly passed as first argument to all non-static member functions.