Create instance of a python class , declared in python, with C API

Question

I want to create an instance of a Python class defined in the `__main__` scope with the C API. For example, the class is called `MyClass` and is defined as follows: ``` class MyClass: def __init__(self): pass ``` The class type lives under `__main__` scope. Within the C application, I want to create an instance of this class. This could have been simply possible with `PyInstance_New` as it takes class name. However this function is not available in Python3. Any help or suggestions for alternatives are appreciated. Thanks, Paul

Accepted Answer

I believe the simplest approach is:

```
/* get sys.modules dict */
PyObject* sys_mod_dict = PyImport_GetModuleDict();
/* get the __main__ module object */
PyObject* main_mod = PyMapping_GetItemString(sys_mod_dict, "__main__");
/* call the class inside the __main__ module */
PyObject* instance = PyObject_CallMethod(main_mod, "MyClass", "");
```

plus of course error checking. You need only DECREF `instance` when you're done with it, the other two are borrowed references.

Create instance of a python class , declared in python, with C API

Solution

Problem