Mastering Python for Finance - Second Edition

Storing the price event handler

Inside the Broker class, add the following two methods as the getter and setter for the price event handler, respectively:

@property
def on_price_event(self):
    """
    Listeners will receive: symbol, bid, ask
    """
    return self.__price_event_handler

@on_price_event.setter
def on_price_event(self, event_handler):
    self.__price_event_handler = event_handler

The inheriting child classes will notify the listeners through the on_price_event method invocation of the symbol, the bid price, and the ask price. Later on, we will use these pieces of basic information for our trading decisions.