Circular Imports

About

• a.py

  # -*- coding: utf-8 -*-
  
  from b import add
  
  def minus(a, b):
      return a - b
  
  if __name__ == '__main__':
      print add(1, 2)
  

• b.py

  # -*- coding: utf-8 -*-
  
  from a import minus
  
  def add(a, b):
      return a + b
  
  if __name__ == '__main__':
      print minus(2, 1)
  

• exec

  $ python a.py
  Traceback (most recent call last):
    File "a.py", line 3, in <module>
      from b import add
    File "/Users/xxx/b.py", line 3, in <module>
      from a import minus
    File "/Users/xxx/a.py", line 3, in <module>
      from b import add
  ImportError: cannot import name addxxxxxxxxxx
  

Solution

• a.py

  # -*- coding: utf-8 -*-
  
  def minus(a, b):
      return a - b
  
  if __name__ == '__main__':
      from b import add
      print add(1, 2)
  

• b.py

  # -*- coding: utf-8 -*-
  
  def add(a, b):
      return a + b
  
  if __name__ == '__main__':
      from a import minus
      print minus(2, 1)
  

• exec

  $ python a.py
  3
  $ python b.py
  1