Compling Python Package via Cython

Question

i am fairly new to cython, does anyone know how to compile a python project via Cython (with relative low overhead), since I keep getting the following import error:

ImportError: No module named CythonRelated.testSource.MyClassObject

My test project structure is like this:

CythonRelated/
           setup.py
           testSource/
                  MainCythonTest.py
                  MyClassObject.py
                  MainCythonTest.pyx   
                  MyClassObject.pyx

Where MainCythonTest imports class from MyClassObject module ( via

from CythonRelated.testSource.MyClassObject import myCustomObj

), initializes an object and calls an object method.

My setup.py looks like this:

from distutils.core import setup
from Cython.Build import cythonize
from distutils.extension import Extension

setup(
    name = "My cython test app",
    ext_modules = cythonize("testSource/*.pyx", include_path = ["."]),
    packages = ["CythonRelated", "CythonRelated.testSource"]
)

What am I missing?

Taking setup.py outside CythonRelated (and obviously updating the corresponding path of *.pyx files in cythonize) didn't help either

MyClassObject.py

import sys
print sys.version_info

class myCustomObj():
    def __init__(self, value):
        self.value_ = value

    def classInfo(self):
        print "calling class {0} object with value of  {1}".format(self.__class__.__name__,
                                                                  self.value_)

MainCythonTest.py

import pyximport; pyximport.install()

from CythonRelated.testSource.MyClassObject import myCustomObj

def myFunc():

    aObj = myCustomObj(12)

    bObj = myCustomObj(21)

    bObj.classInfo()

    aObj.classInfo()

    print "myFunc called"

myFunc()

Answer 1

You need to move the setup.py file anyway, as it cannot be part of a project that it "compiles".

Then, the main issue is that you lack __init__.py files in CythonRelated and CythonRelated/testSource . Without this file, the directory is not an importable Python module. With these two changes, I could pip install --user -e . the package and also run the program MainCythonTest.py