[Python-Dev] Inconsistency in 2.4.3 for __repr__() returning unicode

[Hye-Shik Chang]

We got an inconsistency for __repr__() returning unicode as
reported in http://python.org/sf/1459029 :

class s1:
    def __repr__(self):
        return '\\n'

class s2:
    def __repr__(self):
        return u'\\n'

print repr(s1()), repr(s2())

Until 2.4.2: \n \n
2.4.3: \n \\n

\\n looks bit weird but it's correct.  As once discussed[1] in
python-dev before, if __repr__ returns unicode object,
PyObject_Repr encodes it via unicode-escape codec.  So,
non-latin character also could be in repr neutrally.

But our unicode-escape had a bug since when it is introduced.
The bug was that it doesn't escape backslashes.  Therefore,
backslashes wasn't escaped in repr while it sholud be escaped
because we used the unicode-escape codec.

So, fixing the bug made a behavior inconsistency.
How do we resolve the problem?

Hye-Shik


[1] http://mail.python.org/pipermail/python-dev/2000-July/005353.html