from cPickle import dumps

class foo(object):
    def __reduce__(self):
        raise TypeError, "go away"

class MyFloat(float):
    __slot__ = ('orig')
    def __new__(cls, orig, value):
        self = float.__new__(cls, value)
        self.orig = orig
        return self

    __class__ = property(lambda self: self.orig.__class__)

f = MyFloat(foo(), 1.0)

p = dumps(f)
print `p`