Copy boost.python object

Question

I have several python enhancement classes that I create in python. I want to copy them. So if I have

p = Bernoulli(0.5)

I want to do

q = Bernoulli(p)

But what if I don't know type p? I tried to do this:

q = copy.deepcopy(p)

but python said it cannot sort p.

Is the only solution to add the clone () function to the Bernoulli interface? Or can I somehow create such a method? Can I copy .deepcopy to work with Boost.python objects?

Answer 1

From http://mail.python.org/pipermail/cplusplus-sig/2009-May/014505.html

#define PYTHON_ERROR(TYPE, REASON) \
{ \
    PyErr_SetString(TYPE, REASON); \
    throw bp::error_already_set(); \
}

template<class T>
inline PyObject * managingPyObject(T *p)
{
    return typename bp::manage_new_object::apply<T *>::type()(p);
}

template<class Copyable>
bp::object
generic__copy__(bp::object copyable)
{
    Copyable *newCopyable(new Copyable(bp::extract<const Copyable
&>(copyable)));
    bp::object
result(bp::detail::new_reference(managingPyObject(newCopyable)));

    bp::extract<bp::dict>(result.attr("__dict__"))().update(
        copyable.attr("__dict__"));

    return result;
}

template<class Copyable>
bp::object
generic__deepcopy__(bp::object copyable, bp::dict memo)
{
    bp::object copyMod = bp::import("copy");
    bp::object deepcopy = copyMod.attr("deepcopy");

    Copyable *newCopyable(new Copyable(bp::extract<const Copyable
&>(copyable)));
    bp::object
result(bp::detail::new_reference(managingPyObject(newCopyable)));

    // HACK: copyableId shall be the same as the result of id(copyable)
in Python -
    // please tell me that there is a better way! (and which ;-p)
    int copyableId = (int)(copyable.ptr());
    memo[copyableId] = result;

    bp::extract<bp::dict>(result.attr("__dict__"))().update(
        deepcopy(bp::extract<bp::dict>(copyable.attr("__dict__"))(),
memo));

    return result;
}

To use it:

class_<foo>(foo)
   .def("__copy__", &generic__copy__< foo >)
   .def("__deepcopy__", &generic__deepcopy__< foo >)
   .def(init< const foo & >())

Answer 2

__copy__ __deepcopy__ ( , ++ ) . copy , , .

__copy__:

template<typename T> const T copyObject(const T& v) { return v; }
boost::python::class_<C>("C").def("__copy__", copyObject<C>);

Answer 3

, boost:: python ( ), __setstate__ __getstate__ .

, __getstate__ (python), , __setstate__ .

__init__, __getinitargs__.

. Python docs.