Problem with Dynamically unloading a module

[Steven D'Aprano]

On Wed, 23 Dec 2009 13:37:06 +0100, Jean-Michel Pichavant wrote:

> 3/ if you really need to unload the previous module, it's a little bit
> tedious.
> 
> import mod1
> del mod1
> sys.modules['mod1'] = None 

Assigning sys.modules[name] to None is not the same as deleting the 
entry. None has special meaning to imports from packages, and for modules 
it is interpreted as meaning that the module doesn't exist.

>>> import math
>>> del math
>>> sys.modules['math'] = None
>>> import math
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named math



> # will unload mod1 assuming mod1 was the only
> reference to that module.

Which is highly unlikely. Any classes or functions from the module will 
keep the module alive.


> But believe me, you don't want to mess up with the python import 
> mechanism.

Unless you understand how it works.


-- 
Steven