[C++-sig] ownership of C++ object extended in Python

[Mark Williams]

In the Python FAQ Wiki at http://wiki.python.org/moin/boost.python/HowTo 
I see a heading titled "ownership of C++ object extended in Python" 
which discusses how to keep a PyObject* alive while the object it 
represents still exists in C++. It suggests writing a wrapper as follows:

class MyClassWrap : public MyClass
{
   MyClassWrap( PyObject* self_) : self(self_) { PyINCREF(self); }
   MyClassWrap( PyObject* self_, const MyClass& copy ) : MyClass(copy), 
self(self_) { PyINCREF(self); }
   ~MyClassWrap() { PyDECREF(self); }
   ...
   PyObject *self;
};


I'm guessing (probably incorrectly) that this was written before the 
introduction of boost::python::wrapper<>. What I'd like to do is 
something like..

class MyClassWrap : public MyClass, wrapper<MyClass>
{
	MyClassWrap()
	{
		 Py_INCREF( detail::wrapper_base_::get_owner(*this) )
	}

	~MyClassWrap()
	{
		Py_DECREF( detail::wrapper_base_::get_owner(*this) )
	}

	/* ... wrapped methods here ... */
}

class_<
   MyClass,
   boost::intrusive_ptr<MyClass>,
   boost::noncopyable>("MyClass");

.. but of course get_owner returns 0 from within MyClassWrap()

What is the correct way of incrementing/decrementing the reference count 
for the underlying PyObject* when using wrapper<>, please?

Thanks in advance,

Mark