How to reload Python module in IDLE?

Question

I'm trying to understand how my workflow can work with Python and IDLE.

Suppose I write a function:

def hello():
    print 'hello!'

I save the file as greetings.py. Then in IDLE, I test the function:

>>> from greetings import *
>>> hello()
hello!

Then I alter the program, and want to try hello() again. So I reload:

>>> reload(greetings)
<module 'greetings' from '/path/to/file/greetings.py'>

Yet the change is not picked up. What am I doing wrong? How do I reload an altered module?

I've been reading a number of related questions on SO, but none of the answers have helped me.

Intermingle

ctrl + f6 will restart your session as well. – Undersigned

Answer 1

You need to redo this line:

>>> from greetings import *

after you do

>>> reload(greetings)

The reason just reloading the module doesn't work is because the * actually imported everything inside the module, so you have to reload those individually. If you did the following it would behave as you expect:

>>> import greetings
>>> greetings.hello()
hello!

Make change to file

>>> reload(greetings)
<module 'greetings' from 'greetings.py'>
>>> greetings.hello()
world!

Sommer

Answer 2

Here's what I get when I try your example (from a fresh Python interactive session):

>>> from greetings import *
>>> reload(greetings)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'greetings' is not defined

This indicates the source of the problem. When you use from greetings import *, the name greetings is not imported into the global namespace. Therefore, you cannot use reload(greetings) on it.

To fix this, try the following:

>>> import greetings
>>> greetings.hello()
hello
>>> reload(greetings)
<module 'greetings' from 'greetings.pyc'>
>>> greetings.hello()
hello world

Prate

I think in his example, he left out the fact that he did both import greetings and from greetings import *, so his example above works for him. In that case, reloading greetings alone would not cause a call to hello() to be updated, even though a call to greetings.hello() would work correctly. – Sommer

@Sommer You are probably correct, I've tried a lot of things, and tried to distill the important behavior. – Intermingle

@FarmBoy It's an error I've had happen to me before. I always get an "Oh, duh" feeling after I realize what's going on. – Sommer

Answer 3

IDLE has a menu pick to run the current file. This will restart the shell by running your file first, reloading it.

Broody

Or you could just hit f5 in the file editor (idle) or just use ctrl-f6. Tons easier – Germayne

Answer 4

On windows, I use the shell->Restart shell or CTRL+F6 shortcut to restart and load the latest version of the modue

Grandfather