How to pickle functions/classes defined in __main__ (python)

Question

I would like to be able to pickle a function or class from within __main__, with the obvious problem (mentioned in other posts) that the pickled function/class is in the __m

Answer 1

If you are trying to pickle something so that you can use it somewhere else, separate from test_script, that's not going to work, because pickle (apparently) just tries to load the function from the module. Here's an example:

test_script.py

def my_awesome_function(x, y, z):
    return x + y + z

picklescript.py

import pickle
import test_script
with open("awesome.pickle", "wb") as f:
    pickle.dump(test_script.my_awesome_function, f)

If you run python picklescript.py, then change the filename of test_script, when you try to load the function, it will fail. e.g.

Running this:

import pickle
with open("awesome.pickle", "rb") as f:
    pickle.load(f)

Will give you the following traceback:

Traceback (most recent call last):
  File "load_pickle.py", line 3, in 
    pickle.load(f)
  File "/Library/Frameworks/Python.framework/Versions/7.3/lib/python2.7/pickle.py", line 1378, in load
    return Unpickler(file).load()
  File "/Library/Frameworks/Python.framework/Versions/7.3/lib/python2.7/pickle.py", line 858, in load
    dispatch[key](self)
  File "/Library/Frameworks/Python.framework/Versions/7.3/lib/python2.7/pickle.py", line 1090, in load_global
    klass = self.find_class(module, name)
  File "/Library/Frameworks/Python.framework/Versions/7.3/lib/python2.7/pickle.py", line 1124, in find_class
    __import__(module)
ImportError: No module named test_script