This post originated from an RSS feed registered with Ruby Buzz by Rick DeNatale. Original Post: Alan Kay on the meaning of OOP Feed Title: Talk Like A Duck Feed URL: http://talklikeaduck.denhaven2.com/articles.atom Feed Description: Musings on Ruby, Rails, and other topics by an experienced object technologist. Latest Ruby Buzz Posts Latest Ruby Buzz Posts by Rick DeNatale Latest Posts From Talk Like A Duck

I recently ran into an interesting site with links to "Classical Computer Science Texts", which in turn led me to this e-mail exchange with Alan Kay on the meaning of OOP from July of 2003.

This exchange gives support, with details, for my description of Kay's concept of what Object-Oriented Programming was supposed to mean.

I'm not against types, but I don't know of any type systems that aren't a complete pain, so I still like dynamic typing.
- Alan Kay

As Kay explains, the key concepts came from biological cell communications modeled as networked "whole computers" and a desire to "get rid of with data"

As for the influence of Simula on Smalltalk's notion of classes and inheritance:

I didn't like the way Simula I or Simula 67 did inheritance (though I thought Nygaard and Dahl were just tremendous thinkers and designers). So I decided to leave out inheritance as a built-in feature until I understood it better. - Alan Kay

And summing it up:

OOP to me means only messaging, local retention and protection and hiding of state-process, and extreme late-binding of all things. It can be done in Smalltalk and in LISP. There are possibly other systems in which this is possible, but I'm not aware of them.

I'd argue that you can do this in Ruby as well. I don't know if Ruby was on Kay's radar in mid-2003.