Hi, I am trying to make one class/service hook onto another class/service to add to its functionality without disturbing the original class/service.
My situation is this: I currently have a class which at specific intervals queries one server per instance (via t.u.getProcessOutput()) for some basic information. Each instance has a method which analyses its returned data and stores the result it to ts internal data structure. My dilemma is that I wish to leave this class alone, but I also wish to be able to add functionality from external classes based on the result of said method. For instance: If the method analysing the result from getProcessOutput() discovers a certain user on the server being queried, I wish to store the data to a mysql database. Under other circumstances I wish to send a notification to myself over MSN or via mail. I can easily envision myself wanting to respond to the results with other actions as well in the future. How can this be achieved? I can of course modify the original class so that I pass an adbapi.ConnectionPool as optional argument to __init__() and modify the method to check for the existence of such an object before querying the database. I would then also need to add another optional argument which is whatever object needs to be passed to allow the class to send a message to MSN, and still more optional arguments for any such new service I'd like to add. However, as mentioned I'd rather not modify the original class, and doing this seems like too much of a hack. Or is it? Perhaps inheritance is the key, although that would require me to modify existing methods which I know to be working just to tack on some additional functionality at the end. What are my options here? I took a look at t.p.hook, and it seems like it is perfect for the job: After having instantiated my "global" adbapi.ConnectionPool(), I can just add a pre- or post-hook to any class's method from which I'd like to store data. That way I can make a db-instance which hooks in to any part of my application and stores any result imaginable from any method. However, it seems that t.p.hook is very rarely used, so perhaps there is a better way of achieving what I want? I hope this was somewhat comprehensible, and that there is an elegant solution out there. :) Cheers, Einar _______________________________________________ Twisted-Python mailing list Twisted-Python@twistedmatrix.com http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
