Re: Observer Pattern - Events containing different data

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Tue, 20 Nov 2007 18:28:04 -0500
Message-ID:
<fhvqi0$41c$1@news.datemas.de>
Christopher wrote:

The observer pattern itself is easy enough. I've implemented it using
a Event that contains data for any Event type I forsee my application
using. My problem is I don't want one and only one general purpose
type of Event. I want to write my design in such a way that more Event
Types can be created and used down the road as needed. How can you
design the Events in such a way that more can be handled later by the
same Observer and Subject classes when they don't know what your
Events look like right now?


I am not sure this is a C++ question. Try 'comp.object' as well.

I would probably try to design a polymorphic pair Observer/Event. You
cannot make the same observer observe any type of event, but you can
make more [different] observers to observe the events they know about.
Also, in such case you can make Events aware of the Observers that can
observe them...

V
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