importing imports from your imports in python

Question

Question: In python, Is it wise to use the imports from your sub classes, or does it matter?

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Info:

So, I have a program split up over 6 files. in almost every one of the .py files i import threading, socket, and pickle. What I'm wondering is this, is there an efficiency difference between:

File1.py:

import socket

File2.py:

import File1
import socket

and this:

File2.py:

import File1
from File1 import socket

Or even this:

File2.py

import File1
socket = File1.socket

Answer 1

Don't use from File1 import socket . It doesn't make a performance difference, but it gives headaches to other people having to look in the other file to see that File1.socket is actually socket , and it might get messy if you decide you don't need socket in File1 .

Also, this is against the python principles because:

1. it's not the obvious way to do it
2. flat is better than nested
3. readability counts
4. special cases aren't special enough to break the rules

Answer 2

The import statement is smart enough to realize when a module has already been imported, an not import it again. So:

File.py:

import socket

File2.py:

import File1
import socket

is just fine.

Answer 3

No, there is no efficiency difference. The first approach is the best, since it promotes modularity (like for instance, what if File1.py decides to stop importing socket , then File2.py gets broken)