trouble with reload

Steven D'Aprano steve at REMOVE-THIS-cybersource.com.au
Fri Aug 14 17:24:42 CEST 2009


On Fri, 14 Aug 2009 09:23:17 -0400, Colin J. Williams wrote:

> It's typically a user module that needs to be reloaded.

What's a user module?


> It seems that  del sys.modules['moduleName'] has no effect.

sys.modules is just a dictionary, I find it hard to believe that deleting 
from it has no effect. It works for me:

>>> import sys
>>> import math
>>> 'math' in sys.modules
True
>>> del sys.modules['math']
>>> 'math' in sys.modules
False

What behaviour do you get?


Of course deleting the math module from the cache doesn't do anything to 
the math module in your namespace:

>>> math
<module 'math' from '/usr/lib/python2.5/lib-dynload/mathmodule.so'>
>>> del math
>>> math
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'math' is not defined

Of course deleting the module (or reloading it) doesn't have any effect 
on any objects you already have:


>>> import math
>>> func = math.sin
>>> del sys.modules['math']
>>> del math
>>> math.sin(1.2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'math' is not defined
>>> func(1.2)
0.93203908596722629




> Is there some other way of ensuring that any import goes to
> moduleName.py, instead of moduleName.pyc?

Delete moduleName.pyc.

Make sure the .pyc file doesn't exist in the first place.

Make sure the last modification date of the .py file is newer than the 
modification date of the .pyc file.



-- 
Steven



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