[Python-bugs-list] Error in dictionary comparison (PR#282)

[gpk@bell-labs.com]

Full_Name: Greg Kochanski
Version: 1.5.2
OS: Solaris 2.6
Submission from: h-135-104-50-27.research.bell-labs.com (135.104.50.27)


# The following little chunk of python seems to reveal
# a bug in dictionary comparison or construction.
#
# As can be seen in the printout, the list of keys are
# the same (after sorting).   All the values are one.
# Thus, the two dictionaries ought to compare equal.
# They don't.
#
# Smaller chunks of code don't seem to reveal the problem.

# python bug.py
# a.d= {10: 1, 4: 1, 3: 1, 2: 1, 11: 1} [2, 3, 4, 10, 11]
# b.d= {10: 1, 4: 1, 3: 1, 2: 1, 11: 1} [2, 3, 4, 10, 11]
# Traceback (innermost last):
#  File "bug.py", line 34, in ?
#     test()
#   File "bug.py", line 30, in test
#     assert equals(Set([2, 4, 3, 11, 10]), Set([2, 3, 4, 10, 11]))
# AssertionError



_dicttype = type({})

class Set:
        def __init__(self, a = []):
                if type(a) == _dicttype or type(a) == type(self):
                        self.d = a.copy()
                else:
                        self.d = {}
                        for t in a:
                                self.add(t)

        def add(self, item):
                self.d[item] = 1

        def copy(self):
                return Set(self.d)


def equals(a, b):
        ad = a.d.keys()
        ad.sort()
        print "a.d=", a.d, ad
        bd = b.d.keys()
        bd.sort()
        print "b.d=", b.d, bd
        return Set(b).d == Set(a).d


def test():
        assert equals(Set([2, 4, 3, 11, 10]), Set([2, 3, 4, 10, 11]))


if __name__ == '__main__':
        test()