Mixin vs class decorator

mixin-vs-dec.py

import logging, timeit


class LoggedSetItemMixin(object):
    def __setitem__(self, index, value):
        logging.info('Setting %r to %r' % (index, value))
        super(LoggedSetItemMixin, self).__setitem__(index,value)

class LoggingDict(LoggedSetItemMixin, dict):
    pass

class LoggingList(LoggedSetItemMixin, list):
    pass


def LoggedSetItem(cls):
    orig_setitem = cls.__setitem__
    def __setitem__(self, index, value):
        logging.info('Setting %r to %r' % (index, value))
        return orig_setitem(self, index, value)
    cls.__setitem__ = __setitem__
    return cls

@LoggedSetItem
class DecLoggingDict(dict):
    pass

@LoggedSetItem
class DecLoggingList(list):
    pass


if __name__ == '__main__':
    logging.basicConfig(level=logging.DEBUG)
    dl = LoggingDict()
    dl['a'] = 1

    dd = DecLoggingDict()
    dd['a'] = 2

    logging.getLogger().setLevel(logging.ERROR)

    # 8.46709299088
    print timeit.timeit("d['a'] = 1",
                        "from __main__ import LoggingDict\n"
                        "d = LoggingDict()")

    # 7.8665599823
    print timeit.timeit("d['a'] = 1",
                        "from __main__ import DecLoggingDict\n"
                        "d = DecLoggingDict()")

Hehe, PyPy is wonderful, but closure is still faster than inheritance. Nice to know. :)