Caching tag with singnal-based invalidation

def cached(slot_name, timeout=None):
    def decorator(function):
        def invalidate():
            cache.delete(slot_name)

        def wrapped(*args, **kwargs):
            result = cache.get(slot_name)
            if result is None:
                result = function(*args, **kwargs)
                cache.set(slot_name, result, timeout)
            return result
        wrapped.invalidate = invalidate
        return wrapped
    return decorator

# Here is example usage:

@cached('/data/something_hard')
def get_something_complex():
    ....
    return result

dispatcher.connect(get_something_complex.invalidate, django.db.models.signals.post_save, Model)