> Generic undo of arbitrary domain-object actions with no extra effort.
>
>  AnyObject>> anyMethod
>     Undoable on: [ any side effect block, recursively ]
>
>  or,  Undoable on: [ anyObject anyMethod ]

Get GemStone and use transactions.

Or if you are extremely adventurous use the transactional memory I
implemented in Squeak:
<http://source.lukas-renggli.ch/transactional.html>.

Other than that you probably can't avoid wrapping #anyMethod into a
Command object, as described by the "Design Patterns Smalltalk
Companion" book.

Lukas

-- 
Lukas Renggli
http://www.lukas-renggli.ch