I highly recommend Piumarta: https://www.piumarta.com/software/cola/objmodel2.pdf https://www.piumarta.com/software/cola/objmodel2.pdf A minimal, open-ended, e

I highly recommend Piumarta: https://www.piumarta.com/software/cola/objmodel2.pdf https://www.piumarta.com/software/cola/objmodel2.pdf A minimal, open-ended, end user programmable object runtime model. This paper really changed how I think about classes and objects and their implementation.