Using the observer pattern, ObservableDict can be used to monitor changes to the dictionary.

observable_dict.py

class Observable:
    '''Mixin for objects that need to be observed.'''
    _observers = None

    def observe(self, observer):
        if not self._observers:
            self._observers = []
        self._observers.append(observer)

    def removeobserver(self, observer):
        if observer in self._observers:
            self._observers.remove(observer)

    def notify(self, event):
        for o in self._observers or ():
            o.notify(event)


class ObservableDict(dict, Observable):
    def __setitem__(self, key, value ):
        dict.__setitem__(self, key, value)
        self.notify(("set", key, value))

    def __delitem__(self, key):
        dict.__delitem__(self, key)
        self.notify(("del", key))

    def pop(self, key):
        v = dict.pop(self, key)
        self.notify(("pop", key))
        return v

    def clear(self):
        dict.clear(self)
        self.notify(("clear",))