Boost/Python: How can I use/convert extracted objects?

Question

Suppose:

using namespace boost::python;
void myClass::test(numeric::array& arrayParam) {
    const tuple &shape = extract<tuple>(arrayParam.attr("shape"));
}

I would like to transform it to an int and print for example. I tried int x = shape[0]; but it gives me a "cannot convert ‘boost::python::api::const_object_item’ to ‘int’ in initialization" message.

Answer 1

shape[0] gives you a Python object. To convert it to an int or another C++ type, you need to extract the value:

int x = extract<int>(shape[0]);