Gilad Bracha (co-author of the Java Language Specification) on "#become:" in Smalltalk (https://gbracha.blogspot.com.au/2009/07/miracle-of-become.ht...)

btw, see the section here on "Blub Paradox" (http://www.paulgraham.com/avg.html ) which means I'm not really competent to comment of C#'s dynamic objects.