I applaud your efforts. The fun is in the building, not in the result, so don't worry how impractical it may be. It is a perfect project to enhance your skills with.

Not only should you use strict;, you should embrace Object Oriented Programming concepts. As such, the undo is trivial—copy the object first and throw it away rather than copying it back with changes made. Learning how to architect a large project uses totally different skills than learning how to write in Perl (or whatever language).

—John

Edit 2001-05-30 by mirod: fixed typos