cython cimport from another pyx file - cython

Question

I have a project with the following structure:
lst_viewer/
setup.py
extensions/
instrument.pxd
instrument.pyx
read_events.pyx
src/
lst_viewer/
extensions/
__init__.py
Here is my setup.py file:
import os
from Cython.Distutils import build_ext as cython_build_ext
from setuptools import find_packages, setup
from distutils.core import setup, Extension
EXTENSIONS = [
Extension('lst_viewer.extensions.instrument',sources = [os.path.join('extensions','instrument.pyx')]),
Extension('lst_viewer.extensions.read_events',sources = [os.path.join('extensions','read_events.pyx')]),
]
CMDCLASS = {'build_ext' : cython_build_ext}
setup(name="lst_viewer",
packages=find_packages('src'),
include_package_data=True,
package_dir={'': 'src'},
ext_modules=EXTENSIONS,
cmdclass=CMDCLASS)
Here is my instrument.pxd file:
cdef class Instrument:
cdef int nbdet
cdef class D11Instrument:
pass
cdef Instrument get_instrument(str name)
Here is my instrument.pyx file:
cdef class Instrument:
pass
cdef class D11Instrument(Instrument):
def __cinit__(self):
self.nbdet = 3
cdef Instrument get_instrument(str name):
if name == "D11":
return D11Instrument()
And here is my read_events.pyx file:
from instrument cimport Instrument, get_instrument
def read_events(str instrument_name):
cdef Instrument instr = get_instrument(instrument_name)
I have problems with importing the Instrument class and get_instrument function from the other pyx file of the project (read_events.pyx). Indeed, the code compiles but, when running it, I get a ModuleNotFoundError: No module named 'instrument' error. I tried to add an (empty) __init__.pxd to the lst_viewer/extensions directory but it did not help. Would you have any idea about what I am doing wrong ?