pickle unable to load collection

[paragk]

Hi,

I am unable to figure out the cause of python pickle unable to find
the collection module.

I am getting

    __import__(module)
ImportError: No module named collections

when I try to load a pickled object.

Details:

Python version:

Python 2.6 (r26:66721, Oct  2 2008, 11:35:03) [MSC v.1500 32 bit
(Intel)] on win32


[CODE]

import sys
import glob
import collections
import pickle

...

SomeListDict = collections.defaultdict(list)

... # Populate SomeListDict

DictFile = open (options.saveDict, 'w')
pickle.dump(SomeListDict , DictFile, -1)
DictFile.close()

...

# Try loading the dictionary

LoadDictFile = open(options.loadDict, 'rb')
SomeListDict = pickle.load(LoadDictFile)
LoadDictFile.close()

...
 [CODE END]

The pickle.dump(CallGraphDict, DictFile, -1) works fine. The
dictionary is saved.

The interesting thing is, the dump function is able to find the
collections module.
        try:
            __import__(module)
            mod = sys.modules[module]
            klass = getattr(mod, name)

The above try block succeeds.

module
str: collections

mod
module: <module 'collections' from 'C:\Python26\Lib\collections.pyc'>

klass
type: <type 'collections.defaultdict'>


The SomeListDict = pickle.load(LoadDictFile) fails with

    __import__(module)
ImportError: No module named collections


The sequence of calls is:

    def load_global(self):
        module = self.readline()[:-1]
        name = self.readline()[:-1]
        klass = self.find_class(module, name)
        self.append(klass)
    dispatch[GLOBAL] = load_global

Variables:

module
str: collections

name
str: defaultdict


The code where the exception occurs is:

    def find_class(self, module, name):
        # Subclasses may override this
        __import__(module)
        mod = sys.modules[module]
        klass = getattr(mod, name)
        return klass


>From the above analysis, clearly the collection module exists, since
the dump works.

What am I missing?