#!/usr/bin/python2.7
# -*- coding: utf-8 -*-

import sys

print 'Python version:'
print sys.version
print
print '''Test cPickle with classes derived from Exception.'''

#======================================================================
# Some utility functions

def banner(title, c='-'):
    print c*80
    print title
    print '-'*80

import cPickle

def pickle_unpickle(obj):
    print "before pickle  str(obj):"
    print ">>> '%s'" % obj
    s = cPickle.dumps(obj)
    try:
        tc = cPickle.loads(s)
        print 'after pickle  str(obj):'
        print ">>> '%s'" % tc
    except:
        print "\nunpickling fails  ",
        print "EXCEPTION ### "*3 + "EXCEPTION\n"
        print sys.exc_info()[1]
    return s

#======================================================================
# Pickling/unpickling Exceptions works; example ValueError

print
banner('Class ValueError: pickling/unpickling exceptions works fine.', '=')

t = ValueError('just some custom text in ValueError')
s = pickle_unpickle(t)

#======================================================================
# Now we define a class derived from 'Exception'
# We pickle/unpickle it and get errors, unless we define a class 'Exception'
# ourselves.

class TestException(Exception):
    """Class TestException(Exception): derived class: error occurs, if superclass
'Exception' is not defined in this module!"""
    def __init__(self, msg, details=""):
        self.msg = msg
        self.details = details
    def __str__(self):
        return self.msg

print
banner(TestException.__doc__, '=')

x = TestException('Exception is neither imported nor defined')
s = pickle_unpickle(x)

#----------------------------------------------------------------------

from exceptions import Exception

class TestException(Exception):
    """Class TestException(Exception): derived class: error occurs, even though
superclass 'Exception' is imported!"""
    def __init__(self, msg, details=""):
        self.msg = msg
        self.details = details
    def __str__(self):
        return self.msg

print
banner(TestException.__doc__, '=')

x = TestException('Exception is imported')
s = pickle_unpickle(x)

#----------------------------------------------------------------------

class Exception:
    """Class Exception: our own custom definition of class 'Exception'."""
    def __init__(self, msg, details=""):
        self.msg = msg
        self.details = details
    def __str__(self):
        return 'Exception: ' + self.msg

print
banner(Exception.__doc__, '=')
#----------------------------------------------------------------------

class TestException(Exception):
    """Class TestException(Exception): derived class: NO error occurs, since
we have a custom definition of superclass 'Exception'!"""

    """Class TestException(Exception): Abgeleitete Klasse: KEIN Fehler!
Oberklasse 'Exception' wurde hier im Modul definiert!"""
    def __init__(self, msg, details=""):
        self.msg = msg
        self.details = details
    def __str__(self):
        return self.msg

print
banner(TestException.__doc__, '=')

x = TestException('Exception is custom defined')
s = pickle_unpickle(x)

#======================================================================
# From that I conclude, that something in the definition of 'Exception'
# cannot be pickled.