从定义符号的模块中导入还是从直接导入的模块中导入，是哪一种更好？

Question

Given in the example below, symbol A is defined in module a and imported in b. Module c imports b. Should it access A from module a directly or get it from B (the module it imported directly)? I am thinking of the latter so that I don't need to worry about removing direct references to A, if some day I retire references to b from module c.

a.py

def A(Exception):
    pass

def funA():
    raise A

b.py

from a import A, funA

def funB():
    try:
        funA()
    except A as e:
        # some additional handling
        raise

c.py

import b

# Which of the following is preferred?
# 1. 
try:
    funB():
except a.A:
    # do something

# 2. 
try:
    funB():
except b.A:
    # do something

Answer 1

I recommend the former because:

• The latter is misleading about the origin of the function.
• Using the latter reduces maintainability as you need to traverse b when looking for the function's definition - only to find that it resides in a.
• Moreover, in case you decide to drop module B and directly import A, your code will break.

However, at the end of the day, it boils down to what you and your team prefer. Regardless of what you choose, I recommend that you stay consistent with the choice.