[Python] Automatically encode/decode ctypes argument and return

I have a shared library exposing a function:

const char* foo(const char* s);


To call it from Python using ctypes, I can do the following:

import ctypes

foo = ctypes.cdll.LoadLibrary('foo.so')
foo.foo.argtypes = [ctypes.c_char_p]
foo.foo.restype = ctypes.c_char_p

print(foo.foo('Hello World!'.encode('utf8')).decode('utf8'))


Is there a way to embed the encode/decode('utf8') inside the type itself? I want to do the following:

foo.foo.argtypes = [c_utf8_p]
foo.foo.restype = c_utf8_p

print(foo.foo('Hello World!'))


I was able to handle the argtypes with following:

class c_utf8_p:
@classmethod
def from_param(cls, obj: str):
return obj.encode('utf8')


But cannot figure out the return type. restype docs say assigning it to anything that is not a ctypes type is deprecated, plus truncates value to int which destroys 64-bit pointers. I would like to avoid using errcheck since logically I am not checking any errors, plus it would require setting two attributes for every function.

Continue reading...