PYTHON setup.py build_ext --inplace

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

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

import sys
sys.path.append("path")

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

ext_modules = cythonize(ext_modules, include_path=["include"])


######## pkg/__init__.py ########


######## pkg/a.pxd ########

cdef class A(object):
  pass

######## importer.pyx ########

cimport pkg.a
cimport pkg.a as a
cimport pkg.a as a_by_another_name
from pkg cimport a as from_cimported_a

cdef class A1(a.A):
  pass

cdef class A2(a_by_another_name.A):
  pass

cdef class A3(pkg.a.A):
  pass

cdef class A4(from_cimported_a.A):
  pass