[omniORB] pickling user exceptions

[Luke Deller]

Hi,

We encountered a problem serializing CORBA user exceptions using the
cPickle or pickle modules included with the Python standard library.

The problem is due to the __reduce__ method inherited from BaseException
(Python 2.5+) which assumes that the constructor for subclasses of
BaseException may be called with no arguments.  This is not true for the
exception classes generated by omniIDL.

See attached:
- a simple example of the issue: pickletest.py and pickletest.idl
- a patch to fix the issue: omniORBpy-pickle-exceptions.patch

For reference:
- Python documentation for object.__reduce__:
    http://docs.python.org/library/pickle.html#object.__reduce__
- A thread on the python mailing list regarding a corresponding issue:
    http://mail.python.org/pipermail/python-list/2009-December/1228716.html

Regards,
Luke.

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