A question related to the observer pattern...
Suppose I have a variant: there are stocks, mutual funds, and investors. Let us say that funds are observers for multiple stocks, and investors are observers for funds. Once a "month" all stocks notify their observing funds of their end-of-month price, and *then* all fund to notify their observing investors of their end-of-month investment value.
What is a good way to enforce this timing? (I.e., a fund should not notify an
its investors until all stocks have reported.)
Here is one way:
- for each fund, create a ``reportreceived`` dict that maps stocks to booleans
(initially False)
- as each stock notifies its funds, the fund changes False to True and checks
``all(reportreceived.values())`` to determine whether it is ok to notify
investors.
- When it is ok, the fund notifies investors and resets all the ``reportreceived`` values.
Is this sensible enough? What are standard and better ways?
Thank you,
Alan Isaac
PS I am drawing on the description of the observer pattern at
<URL:http://www.dofactory.com/Patterns/PatternObserver.aspx#_self1>
The real world aspects are just to add some concreteness.
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