Extreme late binding? That's part of it. That resulted in any given code change in a method usually requiring the recompilation of just one method. Much of the

Extreme late binding? That's part of it. That resulted in any given code change in a method usually requiring the recompilation of just one method. Much of the Smalltalk class library was fairly stateless-ish, so you could unwind the top one or two stack frames and restart about 90% of the time.