3

In the game I'm making I'd like to be able to override specific C++ functions with a python functions, as seamlessly as possible. The idea would be to allow quick coding of some functions in an interpreted language for prototyping / modding etc

Ideally I'd like to have a structure behaving like this:

In my C++ source code:

class WorldActions
{
public:

    //example of a method with a default implementation:

    virtual Coordinates respawnLocation(int event) const
    {
        if(event == 0)
            return Coordinates(0,0);
        else
            return Coordinates(1,0);
    }
}

Within a python file:

def respawnLocationOverride(worldActionInstance, event):
    coords = Coordinates()
    coords.x = 1
    return coords

At some point in the C++ engine I dynamically load the python method "respawnLocationOverride" which will effectively replace WorldActions::respawnLocation, this could be done through a special derived class like this :

class WorldActionsFromPy : public WorldActions
{
public:
    virtual Coordinates respawnLocation(int event) const
    {
        if(_something == NULL)
        {
         return WorldActions::respawnLocation(event);
        }
        else
        {
        return _something->callPythonMethod("respawnLocationOverride", this, event);
        }
    }
}

What kind of architecture would you recommend for me to be able to do that as simply as possible? I know I can use swig to generate all the python classes, but I have no idea how I would be able to re-import the python code within a .py file into C++ code

thanks!

Improve this question
5
  • 2
    For something as extensive as this, I would look into Boost for embedded Python: stackoverflow.com/a/982670/4131059 You should be able to load and then reload Python modules as necessary using importlib. Commented Dec 21, 2015 at 15:44
  • Does this mean that both the export of thé c++ code and thé import of the python code are required to both be done via boost? Or could I just use it for half ? Commented Dec 21, 2015 at 19:40
  • Nah, you can actually embed Python inside C++. Or you can export C++ to Python. Boost is quite variable in what it can do, and so if you would like to merely call dynamic Python code from C++, you can do so. Or, you can expose C++ classes to Python, and then call them from Python using importlib to re-load a given module. Commented Dec 21, 2015 at 19:42
  • In your case, you obviously would like to override a given function with an embedded piece of Python code for quick prototyping, so probably the best tutorial would be here: members.gamedev.net/sicrane/articles/EmbeddingPythonPart1.html If this seems productive, I can write a longer answer below. Commented Dec 21, 2015 at 19:47
  • hi ! thanks for the help I've managed to use swig to create a .pyd module that wraps my existing class in Python, so it works well from python, and I can write custom python functions. Now how can I "import" these functions in python and for instance transform my "Coordinate" C++ instance into a "Coordinate" python object ? thanks! Commented Dec 21, 2015 at 22:19
Related questions
2
Porting c++ to python code
6
expose C++ functions in python and embed python in C++
1
Wrapping a piece of C++ code into Python
Load 7 more related questions Show fewer related questions

0

Reset to default

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.