Callback from C++ to Python, how to pass args?

[Bram Stolk]

Hi Christof, thanks for the help.


As for my problem, I will try to state it more clearly.

- I use SWIG to create python support for my class, including shadow classes
- I use a python script to create such an object:

# python script
instance = MyClass();

- I register a python func with an object at some other class:

oc = OtherClass();
oc.SetCallback(mypythonfunc, instance);

- Now, I have a piece of C++ code in OtherClass, that should
  callback the python script func, with a MyClass object as argument.

OtherClass::Call(void)
{
  // make call to registered pythonfunc with instance as arg.
}

It turned out, I could use this code:

      PyObject *func;
      PyObject *instance;

      PyObject *arglist = Py_BuildValue
      (
        "O",
        instance
      );
      PyObject *result = PyEval_CallObject((*ip).func, arglist);

But only if I define some typemaps like:

%typemap(python,in) PyObject *func
{
  $target = $source;
}

and same one for PyObjects called 'instance'.

This strikes me as odd, as the typemaps do not seem to do much.

Using this scheme, I can callback to python funcs, and in those
python funcs, use the MyClass argument as a proper python object.

# callback func
def mypythonfunc(myclassobj)
  print myclassobj;
  myclassobj.somememberfunc();

This seems to work ok now.

Thanks again,

    Bram


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 Bram Stolk, VR Specialist.
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