同时在两个Python脚本之间导入函数

Question

I am trying to run a chat bot of sorts that is capable of creating new commands whilst the program is running. To do this I am keeping all the commands in a second python script and using the main script to edit the commands.py file whilst the chat bot is still running.

The issue...

I am able to have both scripts access each other using import main and then main.functionName() to call the function. However, when I try to call a function in commands.py from main.py, then use the function called to call another function back in main.py I get an error saying

AttributeError: module 'main' has no attribute 'exampleFunction' 

For example the following code;

TESTING.py

import TESTING2

def runme(inp):
    print(inp)
    startOver()

print("begin")
TESTING2.startOver()

TESTING2.py

import TESTING

def startOver():
    userInput = input("Enter text at your own risk... ")
    TESTING.runme(userInput)

Produces the following;

begin
Traceback (most recent call last):
  File "C:\Users\harry\Desktop\TESTING.py", line 1, in <module>
    import TESTING2
  File "C:\Users\harry\Desktop\TESTING2.py", line 1, in <module>
    import TESTING
  File "C:\Users\harry\Desktop\TESTING.py", line 8, in <module>
    TESTING2.startOver()
AttributeError: module 'TESTING2' has no attribute 'startOver'

The desired outcome would be a continuous loop of entering an input and then the text being printed as if one seamless script.

Is this possible? If so how do I do it - or is there a better way to achieve the same goal?

Many thanks.

Answer 1

So, I'll have a go at giving you something that might solve your problem. Essentially what you are doing is constructing a circular dependency: commands.py is written by main.py , main.py depends on commands.py for its functions. There is almost certainly a way to solve your problem without introducing such a circular dependency, but I would need to know more in order to suggest something.

If you are sure you want to do it like this, you could use importlib.reload , which tells python to reload a module that you've already imported. In other words, if you've added a new function to commands.py since calling the original import , calling reload will now make this function available.

As a small example, try setting up commands.py and main.py scripts as follows:

#commands.py
def func1():
    print(1)

and:

#main.py
import commands
commands.func1()

input("hit enter once you've edited commands.py")

from importlib import reload
commands = reload(commands)
commands.func2()

run main.py and when you get to the input part, open up commands.py and change it to look like this:

#commands.py
def func1():
    print(1)

def func2():
    print(2)

Now hit "enter" in the running main.py script. You should see the result of func2 printed to the terminal.

Note however also that reload doesn't necessarily act the way you would expect and could cause some strange and explainable things to happen. For more info, see this post: https://stackoverflow.com/a/438845/141789