How to cythonize a Python-ROS2 package in order to hide the source code?

So I would answer my own question in case someone faced the same issue. For cythonizing your ros2 package in python the best way is adding the required cython components to the setup.py of each package separately. I have marked the cython parts (with <--) for a better understranding.

Please note that after building the package using colcon, a copy of the python source codes would be stored under the install directory produced by colcon. You can easily delete them manually and the package should run with the generated c and shared object files.

from glob import glob
from setuptools import setup
from Cython.Build import cythonize <--
import os

package_name = 'your_package_name_here'

files = package_name + "/*.py"

setup(
    ext_modules=cythonize(files,compiler_directives={'language_level' : "3"},force=True,quiet=True), <--
    name=package_name,
    version='0.0.0',
    packages=[package_name],
    data_files=[
        ('share/ament_index/resource_index/packages',
            ['resource/' + package_name]),
        ('share/' + package_name, ['package.xml']),
        (os.path.join('share', package_name), glob('launch/*.launch.py'))
    ],
    install_requires=['setuptools', "wheel",  "Cython"], <--
    zip_safe=True,
    maintainer='NAME',
    maintainer_email='EMAIL',
    description='TODO: Package description',
    license='TODO: License declaration',
    tests_require=['pytest'],
    entry_points={
        'console_scripts': [
            'SOME CODE HERE',
        ],
    },
)