Reload module if it hasn't been loaded yet in python

Question

I'd like to do the following in python:

check if a module has been imported
if it hasn't, then import the module using import module_name
if it has, then reload the module using importlib.reload(module_name)

I've tried the following, but it doesn't seem to work:

try:
    importlib.reload(module_name)
except NameError:
    import (module_name)

Is there perhaps a better way?

Unless you are writing a debugger or some other specialized code runner, the best thing to do would be to restart your program if the module has been changed. — chepner
– chepner, Commented Jan 24, 2022 at 14:44

user32882 · Accepted Answer · 2022-01-24 15:25:42Z

1

This is the solution, if the module name is only available as a string and not loaded beforehand:

import importlib
import sys

mod_str = "module_name"

if mod_str in sys.modules:
  mod_obj = importlib.import_module(mod_str)
  importlib.reload(mod_obj)
else:
  mod_obj = importlib.import_module(mod_str)

answered Jan 24, 2022 at 15:25

user32882

6,1078 gold badges57 silver badges122 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

ncica · Accepted Answer · 2022-01-24 14:43:52Z

0

A simple way to get modules imported in your Python script is using ModuleFinder (standard Python module).

ModuleFinder class in this module provides run_script() and report() methods to determine the set of modules imported by a script.

Example:

from modulefinder import ModuleFinder
import importlib

finder = ModuleFinder()
finder.run_script('C:/path/your_script.py')

if 'module_name' in finder.modules.keys():
    importlib.reload(module_name)
else:
    importlib.import_module(module_name)

NOTE:

Reload and imoprt are previously imported modules. The argument must be a module object, so it must have been successfully imported before.

edited Jan 24, 2022 at 14:43

answered Jan 24, 2022 at 14:30

ncica

7,2161 gold badge19 silver badges41 bronze badges

3 Comments

user32882 Over a year ago

importlib.reload doesn't accept string arguments. From the docs "The argument must be a module object, so it must have been successfully imported before"

ncica Over a year ago

@user32882 That it is correct, but I have not mentioned anywhere that module_name should be a string argument. there is obviously a difference between 'module_name' and module_name. but in any case I will write an additional note

user32882 Over a year ago

Thanks for the additional note. It turns out I need something where the module has not been imported before...

Collectives™ on Stack Overflow

Reload module if it hasn't been loaded yet in python

2 Answers 2

Comments

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related