Reimport a module in python while interactive

I know it can be done, but I never remember how.

How can you reimport a module in python? The scenario is as follows: I import a module interactively and tinker with it, but then I face an error. I fix the error in the .py file and then I want to reimport the fixed module without quitting python. How can I do it ?

This should work (for Python < 3.4):

reload(my.module)

From the Python docs

Reload a previously imported module. The argument must be a module object, so it must have been successfully imported before. This is useful if you have edited the module source file using an external editor and want to try out the new version without leaving the Python interpreter.

If running Python 3.4 and up, do import importlib, then do importlib.reload(nameOfModule).

Don't forget the caveats of using this method:

• When a module is reloaded, its dictionary (containing the module’s global variables) is retained. Redefinitions of names will override the old definitions, so this is generally not a problem, but if the new version of a module does not define a name that was defined by the old version, the old definition is not removed.

• If a module imports objects from another module using from ... import ..., calling reload() for the other module does not redefine the objects imported from it — one way around this is to re-execute the from statement, another is to use import and qualified names (module.*name*) instead.

• If a module instantiates instances of a class, reloading the module that defines the class does not affect the method definitions of the instances — they continue to use the old class definition. The same is true for derived classes.

In python 3, reload is no longer a built in function.

If you are using python 3.4+ you should use reload from the importlib library instead:

import importlib
importlib.reload(some_module)

If you are using python 3.2 or 3.3 you should:

import imp  
imp.reload(module)  

instead. See http://docs.python.org/3.0/library/imp.html#imp.reload

If you are using ipython, definitely consider using the autoreload extension:

%load_ext autoreload
%autoreload 2

Actually, in Python 3 the module imp is marked as DEPRECATED. Well, at least that's true for 3.4.

Instead the reload function from the importlib module should be used:

https://docs.python.org/3/library/importlib.html#importlib.reload

But be aware that this library had some API-changes with the last two minor versions.

If you want to import a specific function or class from a module, you can do this:

import importlib
import sys
importlib.reload(sys.modules['my_module'])
from my_module import my_function