Trying to set up a dependency in C++ with a parent-child relationship.
The parent contains the child and the child has a weak pointer to the
parent.
I would also like to be able to derive from the parent in Python.
However, when I do this, I get a weak pointer error connecting up this
parent-child relationship.
C++ code:
#include
#include
#include
using namespace boost;
using namespace boost::python;
struct Child;
struct Parent : public enable_shared_from_this<Parent>
{
void initialize();
shared_ptr<Child> m_child;
};
struct Child: public enable_shared_from_this<Child>
{
void setParent(shared_ptr<Parent> ptr);
weak_ptr<Parent> m_parent;
};
void Parent::initialize()
{
shared_ptr<Child> ptr(new Child);
m_child = ptr;
m_child->setParent(shared_from_this());
}
void Child::setParent(shared_ptr<Parent> ptr)
{
m_parent = ptr;
}
static PyObject* create(PyObject* object)
{
PyObject* instance = PyObject_CallObject(object, NULL);
Parent* parent = extract(instance);
parent->initialize();
return instance;
}
Python binding:
BOOST_PYTHON_MODULE(test_module)
{
class_<Parent>("Parent");
def("create", &create);
}
Python code:
from test_module import *
class Test(Parent):
def __init__(self):
Parent.__init__(self)
n = create(Test)
Error:
Traceback (most recent call last):
File "main.py", line 8, in <module>
n = create(Test)
RuntimeError: tr1::bad_weak_ptr
If I try and convert the extracted pointer to Parent into a shared_ptr,
I get a free() invalid pointer error in Python.
Is there a way of getting round this problem or should I give up using
weak pointers with Boost Python?
