In Objective-C, that’s called “method swizzling”, and better supported by the runtime. See https://nshipster.com/method-swizzling/

And of course, Common Lisp has “change-class” (https://www.snellman.net/blog/archive/2015-07-27-use-cases-f..., discussed at https://news.ycombinator.com/item?id=734025) and Smalltalk has “become:” (https://gbracha.blogspot.com/2009/07/miracle-of-become.html. Short discussion at https://news.ycombinator.com/item?id=734025)