How to properly reload a module in Python

Question

This question has been asked many times, here are a few for reference:

Proper way to reload a python module from the console

How to reload a module's function in Python?

From what I searched and learned, I have wrote the following but it fails to properly reload the module:

import pandas as pd

pd.get_option('display.width')  # 80

pd.set_option("display.width", 150)

del pd

import importlib

import sys

pd = importlib.reload(sys.modules['pandas'])

pd.get_option('display.width')  # 150

alko · Accepted Answer · 2024-08-17 13:29:26Z

1

Your module (pandas) in this case is actually reloaded, but importlib.reload does not clear internal memory of module-level variables, it merely re-executes the module’s code. Now, the value of the module variables after reload depends on the way it was initialized. If you define your module m.py like

x = 0
try:
    y
except NameError:
    y = 0

you can see the difference in behavior:

>>> import importlib
>>> import m
>>> m.x
0
>>> m.y
0
>>> m.x = 1
>>> m.y = 1
>>> _ = importlib.reload(m)
>>> m.x
0
>>> m.y
1

answered Aug 17, 2024 at 13:29

alko

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1 Comment

Shayan Over a year ago

Ah this makes so much sense, thank you. I guess it's best to run my code in a new process then. The Python imports has been a recurring issue for me especially when I'm making a small web interface using Google's Mesop along with using config managers such as yacs.

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