Python pickling after changing a module's directory

Question

I\'ve recently changed my program\'s directory layout: before, I had all my modules inside the \"main\" folder. Now, I\'ve moved them into a directory named after the progra

Answer 1

pickle serializes classes by reference, so if you change were the class lives, it will not unpickle because the class will not be found. If you use dill instead of pickle, then you can serialize classes by reference or directly (by directly serializing the class instead of it's import path). You simulate this pretty easily by just changing the class definition after a dump and before a load.

Python 2.7.8 (default, Jul 13 2014, 02:29:54) 
[GCC 4.2.1 Compatible Apple Clang 4.1 ((tags/Apple/clang-421.11.66))] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import dill
>>> 
>>> class Foo(object):
...   def bar(self):
...     return 5
... 
>>> f = Foo()
>>> 
>>> _f = dill.dumps(f)
>>> 
>>> class Foo(object):
...   def bar(self, x):
...     return x
... 
>>> g = Foo()
>>> f_ = dill.loads(_f)
>>> f_.bar()
5
>>> g.bar(4)
4