Oh, if you are big on separation maybe you can confirm something I suspect, namely that Cells, by allowing different instances of the same class to have different rules for the same slot, makes OO design.

For example, one can have a game normally look like:

   (make-instance 'game
        :speed (c? (* (^difficulty-slider) 500))...

But then for debugging a hard problem you might want to play back a log at full speed and so the replay code goes:

   (make-instance 'game :speed 500...

In the first case the game /instance/ is being driven by the GUI slider widget, but the game /class/ does not know about the GUI.

Does that make sense in resolving the separation issue?

ken