@jessenoller lunch break challenge : http://twitter.com/#!/jessenoller/status/43371023306981376

suicidal_key.py

from threading import Timer

class SuicidalKey(object):
    """
    >>> k = SuicidalKey("asdf",30)
    >>> k.key
    'asdf'
    >>> # Before 30 seconds are up
    >>> k.reset_expiration(30)
    >>> # Wait 30 seconds
    >>> k.key
    None
    """
    def __init__(self, key, expiration_time=300):
        self.key = key
        self.__expire_timer = Timer(0,None)
        self.reset_expiration(expiration_time)
    def __expire_key(self):
        self.key = None
    def reset_expiration(self, expiration_time=300):
        if self.key:
            self.__expire_timer.cancel()
            self.__expire_timer = Timer(expiration_time, self.__expire_key)
            self.__expire_timer.start()

import time

class Value(object):
    def __init__(self, value):
        self.value = value
        self.timestamp = time.time()

class ExpireDict(dict):
    def __init__(self, expire_time):
        self.expire_time = expire_time

    def __setitem__(self, key, value):
        dict.__setitem__(self, key, Value(value))

    def __getitem__(self, key):
        val = dict.__getitem__(self, key)
        if time.time() - val.timestamp > self.expire_time:
            del self[key]
            raise KeyError(key)
        else:
            return val.value

    # other dict methods overridden

if __name__ == '__main__':

    d = ExpireDict(2)

    d["a"] = "b"
    d["b"] = "c"

    time.sleep(1)

    assert d["a"] == "b"

    time.sleep(1)

    try:
        d["a"]
        assert False
    except KeyError:
        pass

zzzeek: consider using an abc instead so you can have full control on where the key is removed. Your implementation will fail by exchanging d["a"] with "a" in d, as an example.

yup, many methods will fail in this partial example including d.values(). was just to illustrate the method of associating timestamp.