[C++-sig] Re: Extracting C++ objects: documentation example fails.

[Mike Rovner]

Joel Gerard wrote:

> I'm trying to extract some wrapped objects from a python script in
> C++. I've tried running the example from the docs to see how extract
> works, but it wont compile:
>
> struct X
> {
>    X(int x) : v(x) {}
>    int value() { return v; }
>  private:
>    int v;
> };
>
> foo()
> {
>     object x_class(
>        class_<X>("X", init<int>())
>           .def("value", &X::value))
>           ;
>
>     // Instantiate an X object through the Python interface.
>     // Its lifetime is now managed by x_obj.
>     object x_obj = x_class(3);
>
>     // Get a reference to the C++ object out of the Python object
>     X& x = extract<X&>(x_obj);
>     assert(x.value() == 3);

Extract means smthng different, e.g. extracting a value

      int x = extract<int>(x.obj.attr("value"));

> I'm using VC 7.

Don't! Use VC7.1

HTH,
Mike