Your question moved the goalposts. Making change to a running system wasn't part of db48x's claim to which dleslie responded. It was explicitly excluded, in fact.

ok, fair, but what i am asking about is a feature of common lisp (and smalltalk or pike), so i didn't pay attention to the exclusion. that was not deliberate. my bad. (maybe you could say i moved the goalpost back to the original topic)