On 09/24/2010 02:42 PM, Simon W wrote:
Hey, sorry for the lacking information.
May I declare it as this instead:
C++ Class
class GameObjectManager
{
map<GameObject*, Data> a_map; // this map has "nothing" to do with
python dict
GameObject* createGameObject(id)
{
Gameobject* obj = new Gameobject(id);
a_map[ obj ] = ...some data...
return obj;
}
callPython()
{
// get game object from map
obj = a_map.getgameobject()
boost::python::get_override("callbackFunction")(boost::python::object(boost::python::ptr(obj)));
}
}; // end of class
The python class:
class myRandomClass:
def __init(self, the_c++_GameobjectManager_pointer):
self.manager = the_c++_GameobjectManager_pointer
gameobject = self.manager.createGameObject(1)
#self.manager.createGameObject() returns a pointer to the gameobject
created in c++
self.mylist[gameobject] = ..some data..
def callPython(self, gameobj): # at some point, c++ will call this
function and pass the game object we created above with id 1
for x in self.mylist.keys():
print(x == gameobj) # True
print(gameobj in mylist) # False
So basically the c++ class and python class have their own dict but I
want them to have the *same *address value in their keys .. is it possible??
It seems, in c++ the key is the address of the game object and in Python
it some other address (but they basically point to the same
object/memory). Is there any way around this _without_ changing the type
of the key being used, i.e. keep the key as a pointer.
You need to define __eq__, __ne__ and __hash__ in Python in such a way
that they compare the C++ pointers for equality. You can do this by
writing free functions that take a GameObject* as their first argument,
and wrapping them as Python methods with those special names.
That should be all you need to do.
Be aware that defining __hash__ also tells Python that you promise that
it's return value is an immutable property of the Python object - i.e.
the same Python object should never be changed to point to a different
C++ object (this is hard to do accidentally anyhow in Boost.Python).
Jim
On Fri, Sep 24, 2010 at 4:27 PM, Stefan Seefeld <seef...@sympatico.ca
<mailto:seef...@sympatico.ca>> wrote:
Simon,
I don't quite understand what you are trying to do. Please provide a
little more detail. Your current mail requires far too much
second-guessing to be useful.
On 09/24/2010 10:08 AM, Simon W wrote:
Hi,
Im really scared because I fear a fundamental issue concerning
the script system in my game engine.
In C++, I have a class. In my class I map data to GameObject like:
*class
{
map<GameObject*, Data> .....
}*
OK. (Naming this class would help the discussion, though.)
As you see, I use the pointer as key.
When I from c++, in the same class, call a python function I
pass the key like this:
*class::callPythonFunctions()
{
boost::python::get_override("callbackFunction")(boost::python::object(boost::python::ptr(gameobject)));
// the variable /gameobj /is of type GameObject*
}
*
OK.
When I recieve the call in python I do some checks like this:
*def callbackFunction(self, gameobj):
for x in self.mydict.keys():
print("Checking")
print(gameobj == self.mydict)
print(gameobj in self.mydict)*
This looks wrong. You iterate over 'x', but don't use it in the
loop. May I assume that 'mydict' relates to the above
map<GameObject*, Data> in the unnamed class ?
The above will print something like:
/....
Checking
True
False
.../
This suggests that 'gameobj' compares equal to the 'mydict' object,
but that it is not itself included in the sequence returned by
mydict.keys().
I do have a overloaded == operator. But how can I fix so that
python checks for my pointer and not the PyObject* pointer ?
What type do you consider providing an operator== for ?
Stefan
--
...ich hab' noch einen Koffer in Berlin...
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