Passing multiple arguments to C function within Python

Question

Let's say I have a c library that manipulates a world somehow.

I want to use this library with python. I want to be able to write simple python scripts that represent different scenarios of world management.

I have functions that create and destroy a world: void* create(void); int destroy(void* world);

Here is some python code:

import ctypes

lib = ctypes.CDLL('manage_world.so')

_create = lib.create
_create.restype = ctypes.c_void_p

_destroy = lib.destroy
_destroy.argtypes = [ctypes.c_void_p,]
_destroy.restype = ctypes.c_int

def create_world():
    res =  _create()
    res = ctypes.cast(res, ctypes.c_void_p)
    return res

def destroy_world(world):
    return _destroy(world)

new_world = create_world()
print type(new_world)

print destroy_world(new_world)

Now I want to add functions like: int set_world_feature(void* world, feature_t f, ...); int get_world_feature(void* world, feature_t f, ...);

The thing is that in my python wrapper I don't know how to pass variously multiple arguments.

Because sometimes set_world_feature() is called with 3 or 4 arguments.

In Python again:

def set_world_feature(world, *features):
    res = lib.set_world_feature(world, *features)
    return world_error[res]

How to fix this in order for it to work?

Luper Rouch · Accepted Answer · 2010-01-28 16:13:23Z

1

When you do:

def create_world():
    return _create

You don't call _create, so create_world returns the function pointer. If you want the pointer to your world instance you should write instead:

def create_world():
    return _create()

answered Jan 28, 2010 at 16:13

Luper Rouch

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