avoid duplicating default parameters in Cython

.gitignore

build/
pycode.cpp
pycode.so

cppcode.cpp

// file: cppcode.cpp
#include "cppcode.hpp"
#include <iostream>

int init(const char *address, int port, bool en_msg, int error) {
  using namespace std;
  if (not address) return ++error;
  std::cout << address << " " 
            << port << " " 
            << boolalpha << en_msg << " " 
            << error << std::endl;
  return error;
}

cppcode.hpp

// file: cppcode.hpp
int init(const char *address=0, int port=0, bool en_msg=false, int error=0);

cppcode.pxd

# file: cppcode.pxd
cdef extern from "cppcode.hpp":
     int init(char *address, int port, bint en_msg, int error)
     int init(char *address, int port, bint en_msg)
     int init(char *address, int port)
     int init(char *address)
     int init()

Makefile

# file: Makefile
.PHONY: test clean

test: pycode.so
	python test_pycode.py

pycode.so: pycode.pyx setup.py cppcode.pxd cppcode.cpp cppcode.hpp
	python setup.py build_ext -i

clean:
	-rm *.so pycode.c* build/ -r 

pycode.pyx

# file: pycode.pyx
cimport cppcode

class Unset(object):
    def __nonzero__(self):
        raise TypeError("a boolean is required")
UNSET = Unset()

def init(address=UNSET,port=UNSET,en_msg=UNSET,error=UNSET):
    if error is not UNSET:
        return cppcode.init(address, port, en_msg, error)
    elif en_msg is not UNSET:
         return cppcode.init(address, port, en_msg)
    elif port is not UNSET:
         return cppcode.init(address, port)
    elif address is not UNSET:
         return cppcode.init(address)
    return cppcode.init()

setup.py

# file: setup.py
from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext

setup(
    cmdclass = {'build_ext': build_ext},
    ext_modules = [Extension("pycode", ["pycode.pyx", "cppcode.cpp"],
                             language="c++",)] # libraries=["stdc++"])]
)

test_pycode.py

# file: test_pycode.py
"""
>>> pycode.init()
1
>>> pycode.init(port=123) #doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
TypeError:
>>> pycode.init("address", port=123)
0
>>> pycode.init("address", 123, error=2) #doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
TypeError:
>>> pycode.init("address", error=2) #doctest: +IGNORE_EXCEPTION_DETAIL
Traceback (most recent call last):
...
TypeError:
"""
import pycode

pycode.init("address")