[C++-sig] operator in return false while operator == return true

[Simon W]

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.




On Fri, Sep 24, 2010 at 4:27 PM, Stefan Seefeld <seefeld at 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...
>
> _______________________________________________
> Cplusplus-sig mailing list
> Cplusplus-sig at python.org
> http://mail.python.org/mailman/listinfo/cplusplus-sig
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/cplusplus-sig/attachments/20100924/103430c8/attachment.html>