I get the complaint about one more OO system, but I did consider all the options and I&#x27;m pretty sure that this was the best solution, given how few people will be exposed to it.<p>There&#x27;s also a legitimate learning challenge: if I want to figure out which OO system is best for most projects, I have to try them all out. And then the payoff for translating to a common system is small.<p>That said, for new projects I pretty much use S3 and R6 exclusively. (And it is legitimate to have two systems because they are so different and R6 is mostly needed for internal mutability)