PYTHON setup.py build_ext --inplace

######## setup.py ########

from Cython.Build import cythonize
from Cython.Distutils.extension import Extension

ext_modules = [
    Extension("foo", ["foo.pyx"]),
]

# Example documented in docs/src/reference/compilation.rst
from Cython.Build.Dependencies import default_create_extension

def my_create_extension(template, kwds):
    libs = kwds.get('libraries', []) + ["mylib"]
    kwds['libraries'] = libs
    return default_create_extension(template, kwds)

ext_modules = cythonize(ext_modules, create_extension=my_create_extension)

assert ext_modules[0].libraries == ["mylib"]

######## foo.pyx ########