"""
Figure out how __str__ and __unicode__ class methods are used
when str() and unicode() are called on the class, in all combinations.

I submitted a bug re Python documentation for this:
http://bugs.python.org/issue9196


Example 1:
    "%s" % test_object

From what I can tell, in this case:
1. test_object.__str__() is called.
2. If test_object.__str__() returns a string object, then that is substituted.
3. If test_object.__str__() returns a Unicode object (for some reason), then
    test_object.__unicode__() is called, then _that_ is substituted instead.
    The output string is turned into Unicode. This behaviour is surprising.
4. If test_object.__str__() returns a Unicode object (for some reason), and
    test_object.__unicode__() does not exist, then the Unicode value from the
    __str__() call is used as-is (no conversion to string, no encoding errors).
    This is also a little surprising [in this situation unicode(test_object)
    also returns the Unicode object returned by __str__() as-is, so I guess
    there's some consistency there].

[Note that the call to test_object.__str__() is not the same as
str(test_object), because the former can return a Unicode object without
causing an error, while the latter, if it gets a Unicode object, will then try
to encode('ascii') to a string, possibly generating a UnicodeEncodeError exception.]


Example 2:
    u"%s" % test_object

In this case:
1. test_object.__unicode__() is called, if it exists, and the result is
    substituted. The output string is Unicode.
2. If test_object.__unicode__() doesn't exist, then test_object.__str__() is
    called instead, converted to Unicode, and substituted. The output string is
    Unicode.


Example 3:
    "%s %s" % (u'unicode', test_object)

In this case:
1. The first substitution causes the output string to be Unicode.
2. It seems that (1) causes the second substitution to follow the same rules as
    Example 2. This is a little surprising.
"""

class TestObject:
    def __str__(self):
        return u"String\u4422"
#    def __unicode__(self):
#        return u"Unicode"

test_object = TestObject()
out = "%s %s" % ('str', test_object)
print "__str__():", repr(test_object.__str__())
print "out:", repr(out)
print "type(out):", type(out)
#print "str():", repr(str(test_object))
print "unicode():", repr(unicode(test_object))