I've basically have a very simple node test case I'm trying to fix.
I have a simple Node class with a getChild and a getParent
The child can be assigned via the addChild function
Then this function automatically set the parent on the relevant class (so from the c++ side)
Unfortunately when I do that I lose the python reference..
I guess the code should be better to understand :
the basic main class MyNode :
class MyNode
{
public:
MyNode(): m_name("unknown") {}
MyNode(std::string name): m_name(name) {}
MyNode(MyNode * const o) : m_name(o->m_name) {}
virtual ~MyNode() {}
std::string getName() const { return m_name; }
void setName(std::string name) { m_name = name; }
boost::shared_ptr<MyNode> getChild() const { return m_child; }
const boost::shared_ptr<MyNode> & getParent() const { return m_parent; }
void addChild(boost::shared_ptr<MyNode> node) {
m_child = node;
node->m_parent = boost::make_shared<MyNode>(this);
}
private:
std::string m_name;
boost::shared_ptr<MyNode> m_parent;
boost::shared_ptr<MyNode> m_child;
};
Then the boost python bindings code :
class_< MyNode, boost::shared_ptr<MyNode>/*, MyNodeWrapper*/ >("MyNode", init<std::string>())
.add_property( "Name", &MyNode::getName, &MyNode::setName )
.add_property( "Child", &MyNode::getChild )
.add_property( "Parent", make_function(&MyNode::getParent, return_internal_reference<>()))
.def( "addChild", &MyNode::addChild )
;
To finish my python test code :
>>> p=MyNode("p")
>>> o=MyNode("o")
>>> p.addChild(o)
>>> o.Parent
<hello_ext.MyNode object at 0x01C055A8> << this is not equal to p
>>> p
<hello_ext.MyNode object at 0x01C06510> << as you can see p here
>>> o.Parent
<hello_ext.MyNode object at 0x01C055A8> << but at least the pointer doesn't change each time the Parent is called !
>>> p.Child == o << so for the child it works
True
>>> o.Parent == p << but it doeesn't work for Parent
False
The issue is certainly in the addFunction and how I use boost::make_shared to set the parent. I unfortunately have no idea what's going on.. I've tried to use a boost wrapper:
struct MyNodeWrapper : public MyNode, public boost::python::wrapper<MyNode>
{
MyNodeWrapper( PyObject * a_PyObj ) : m_Self( a_PyObj ) {}
MyNodeWrapper( PyObject * a_PyObj, const MyNode & a_Vec ) : MyNode( a_Vec ), m_Self( a_PyObj ) {}
MyNodeWrapper( PyObject * a_PyObj, std::string name ) : MyNode( name ) , m_Self( a_PyObj ) {}
PyObject * m_Self;
};
But still I'm not sure how I should modify the addChild function
Any idea ?
You can't do this:
node->m_parent = boost::make_shared<MyNode>(this);
Without boost::enable_shared_from_this
. See What is the usefulness of `enable_shared_from_this`?
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.