[ python-Bugs-1699759 ] pickle example contains errors

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Bugs item #1699759, was opened at 2007-04-13 02:22
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Category: Documentation
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Mark Edgington (edgimar)
Assigned to: Nobody/Anonymous (nobody)
Summary: pickle example contains errors

Initial Comment:
In the pickle documentation (see http://docs.python.org/lib/pickle-example.html ), there is an error.  At the end of the page, under the "A sample usage might be..." section, the file for dumping is opened in text-mode instead of binary mode.

This bit me because I was lazy and didn't re-read all of the pickle documentation, but based some code on this snippet.  The problem occurs under certain circumstances when pickling a type 'object' instance (newstyle) under Windows, and then attempting to unpickle it under Linux.  You get the following error: ImportError: No module named copy_reg.  This made no sense to me, and it took a long time to figure out that the problem was due to the mode in which the file was saved (what that has to do with the ImportError I still have no idea...).  If interested, I could attach a test script which is supposed to load the data to a class instance, and two pickle dumps, one which works, and the other which fails.

Perhaps a related suggestion which maybe should be in a different bug is that pickle should check to see when it writing to a filehandle if the filehandle's mode is binary or text, and to issue a warning if it is text.


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