calldules.py

import ctypes


# Create a function prototype for a 3-arg function
ternaryfunc = ctypes.CFUNCTYPE(ctypes.py_object, ctypes.py_object,
                               ctypes.py_object, ctypes.c_void_p)


# Define a new python type that's callable, via a ternaryfunc
class PyTypeObject(ctypes.Structure):
    _fields_ = (
        ("ob_refcnt", ctypes.c_ssize_t),
        ("ob_type", ctypes.c_void_p),
        ("ob_size", ctypes.c_ssize_t),
        ("tp_name", ctypes.c_char_p),
        ("tp_basicsize", ctypes.c_ssize_t),
        ("tp_itemsize", ctypes.c_ssize_t),
        ("tp_dealloc", ctypes.c_void_p),
        ("tp_print", ctypes.c_void_p),
        ("tp_getattr", ctypes.c_void_p),
        ("tp_setattr", ctypes.c_void_p),
        ("tp_reserved", ctypes.c_void_p),
        ("tp_repr", ctypes.c_void_p),
        ("tp_as_number", ctypes.c_void_p),
        ("tp_as_sequence", ctypes.c_void_p),
        ("tp_as_wrapping", ctypes.c_void_p),
        ("tp_hash", ctypes.c_void_p),
        ("tp_call", ternaryfunc),
        ("tp_str", ctypes.c_void_p),
    )


# And define a python object whose type is the one above
class PyObject(ctypes.Structure):
    _fields_ = (
        ("ob_refcnt", ctypes.c_ssize_t),
        ("ob_type", ctypes.POINTER(PyTypeObject)),
    )


@ternaryfunc
def module_call(obj, args, kwargs):
    if kwargs:
        kwargs = ctypes.cast(kwargs, ctypes.py_object).value
    else:
        kwargs = {}
    # See if module contains an class named Module, instantiate it
    if hasattr(obj, obj.__name__.title()):
        prop = getattr(obj, obj.__name__.title())
    # or see if it similarly has a class named module
    elif hasattr(obj, obj.__name__):
        prop = getattr(obj, obj.__name__)
    else:
        return
    try:
        return prop(*args, **kwargs)
    except TypeError as e:
        ## Well this doesn't work either.
        raise e

# Load a module object into our new PyObject
ctypes_mod = PyObject.from_address(id(ctypes))
# Grab its type's contents
ctypes_mod_ob_type = ctypes_mod.ob_type.contents
# Assign its callable to our module_call function
ctypes_mod_ob_type.tp_call = module_call
# Your modules can now be called!