<p>Is it possible to create custom events in C++?  For example, say I have the variable X, and the variable Y.  Whenever X changes, I would like to execute a function that sets Y equal to 3X.  Is there a way to create such a trigger/event?  (triggers are common in some databases)</p>

Think you should read a little about
Design Patterns
, specifically the
Observer Pattern
.
Qt from
Trolltech
have implemented a nice solutions they call
Signals and Slots
.