Question

In python 2.6, I defined a class Abc, made a dict d where keys are strings and values are abc objects. Then I dumped this dict to a file like this-
pickle.dump(d, open(‘filename.pkl’, ‘wb’))

I can successfully load it python 2.6 with

d1 = pickle.load(open('filename.pkl', 'rb'))

(d1 is identical to d)

But when I try to load it in python 3.1, only the first key (string) is loaded

d1 = pickle.load(open('filename.pkl', 'rb'))

print(d1)
keyname1

The pickled file starts like

(dp0
S'keyname1'
p1
(iabc
ABC
p2 

So it seems like in 3.1, it’s only loading the first string in the file. I don’t know much about encoding etc. Any ideas on what I can do to load my dict d in 3.1.1?

Edit- my class (abc.py) is in the same working directory both times, not sure if this matters?

Edit after answer- I realized I should have clarified better so it can be reproduced easily. My code was buggy both because of the name clash and because I wasn’t defining my class correctly.

Anyways, I just tried the following and learnt that I should start classes with class ABC(object): rather than just class ABC. And that I should delete .pyc files before importing a module the second time.

What I did —

Try 1

ABC.py

class ABC():
   pass

in python-2.6

import pickle
import ABC
d = {'keyname1': ABC.ABC()}
pickle.dump(d, open('filename.pkl', 'wb'))
quit()

in python-3.1

import pickle
d1 = pickle.load(open('filename.pkl', 'rb'))
print(d1)
 keyname1
quit()

Try 2

But when I changed the class definition in ABC.py so it said class ABC(object): instead of just class ABC:, removed the old filename.pkl, ABC.pyc and repeated,

in python-2.6

# same as before

in python-3.1

import pickle
d1 = pickle.load(open('filename.pkl', 'rb'))
print(d1)
{'keyname1': <ABC.ABC object at 0x638890>}

Answer 1

The following works fine with Python 2.6.6 and Python 3.1.3:

Python 2.6 code:

import pickle

class ABC(object):
    pass
d = {'keyname1': ABC()}

# Dump!
pickle.dump(d, open('filename.pkl', 'wb'))

Python 3.1 code:

import pickle

class ABC(object):
    pass

# Load:
d1 = pickle.load(open('filename.pkl', 'rb'))

print(d1)

The result is:

{'keyname1': <__main__.ABC object at 0x8c99eec>}

So clearly loading the ABC object worked fine.
I think the problem is that you have a name clash between your module abc and the module called abc in the standard library, and that this name clash behaves differently in Python 2 and Python 3.

Solution: Rename your module.