Damien Cassou wrote Thanks for the reply. What I was pondering was the apparent mismatch between the memento way of object creation and class-side instance creation methods which need some information passed to them to determine which subclass to actually return an instance of. I guess what I need is something like: MySuperclass new asMorph addButtons; addWindow; onAnswer: [ :e | subclassInstance := MySuperclass instanceCreationMessage: e releventInformation ]; openInWorld. ----- Cheers, Sean -- View this message in context: http://forum.world.st/Instance-Creation-Pattern-tp4709470p4710332.html Sent from the Magritte, Pier and Related Tools mailing list archive at Nabble.com.