Need to re-load libraries in Python, with Canopy

Question

I am working on a python project with Canopy, using my own library, which I modify from time to time to change or add functions inside.

At the beginning of myfile.py I have from my_library import * but if I change a function in this library and compute again myfile.py it keep using the previous version of my function.

I tried the reload function :

import my_library
reload(my_library)
from other_python_file import *
from my_library import *

and it uses my recently changed library.

But if it is :

import my_library
reload(my_library)
from my_library import *
from other_python_file import *

It gives me the result due to the version loaded the first time I launched myfile.py.

Why is there a different outcome inverting the 3rd and 4th line ?

Possible duplicate of [How do I unload (reload) a Python module?](http://stackoverflow.com/questions/437589/how-do-i-unload-reload-a-python-module) — Styrke, Apr 21 '17 at 13:05
Possible duplicate of [Reload Python module](http://stackoverflow.com/questions/27899348/reload-python-module) — Panagiotis Simakis, Apr 21 '17 at 13:36
@Simakis Panagiotis : The problem in the question you mention is that there is no "import my_module" but I put it. That's not the same problem. — trapuck, Apr 21 '17 at 13:47

score 0 · Accepted Answer · answered Apr 21 '17 at 18:52

Without seeing the source code, it's hard to be certain. (For future reference, it is most useful to post a minimal example, which I suspect would be about 10 lines of code in this case.)

However from your description of the problem, my guess is that your other_python_file also imports my_library. So when you do from other_python_file import *, you are also importing everything that it has already imported from my_library, which in your second example, will override the imports directly from my_library (Since you didn't reload other_python_file, it will still be using the previous version of my_library.)

This is one out of approximately a zillionteen reasons why you should almost never use the form from xxx import * except on the fly in interactive mode (and even there it can be dangerous but can be worth the tradeoff for the convenience). In a python source file, there's no comparable justification for this practice. See the final point in the Imports section of PEP-8.

(Edited answer to explain why other_python_file still uses previous version of my_library) — Jonathan March, Apr 21 '17 at 18:56

Need to re-load libraries in Python, with Canopy

1 Answers1