AutomaticCythonImport

amodulename = 'modulename'
 
try:
  import pyximport
  pyximport.install()
except:
  print('Cython import failed; {0} will use the legacy (pure Python) mode.'.format(amodulename))
  from modulenamevanilla import class1, class2, class3
else:
  try:
    from modulename import class1, class2, class3
  except ImportError:
    print('Could not build/import {0}.pyx; {0} will use the legacy (pure Python) mode.'.format(amodulename))
    from modulenamevanilla import class1, class2, class3

This is the magic ingredient to make your Cython module compile automatically when imported (with a pure-Python fallback).