On Mon, Nov 13, 2017 at 1:54 PM, Bob Myers <[email protected]> wrote: > You should review the TypeScript approach to mixins: > https://www.typescriptlang.org/docs/handbook/mixins.html. >
This seems very similar to the naive approach based on Object.assign that I mention in the first message of this thread. Please see the disadvantages that I mention there and also note that this approach doesn't provide the ability to share private state. > But more generally, mixins are a very specific, opinionated OO design > pattern. They are probably misused more often than not. If you think that > big class hierarchies were brittle and hard to maintain, just wait until > you include mixins. > Could you please provide some more details? The advantages of my approach to mixins in comparison to other approaches that I mentioned in the first message also apply in comparison to inheritance. > There are many, many alternatives to modeling things like "can move more > than one square at a time in some direction", and most of them are, at > least in my opinion, superior to mixins. > The chess example is just an example. What mixins achieve in general is sharing a partial definition of a concept in multiple places. Can you please mention a few of the many, many superior alternatives to achieve this (please note I'm also interested in using private state)? > It is also not too hard to make the case that mixins are somewhere between > difficult and impossible to implement properly in a language which doesn't > have proper built-in support--the fundamental notion of prototypes in JS, > which underlies its classes, can be considered mixin-hostile. > > Did you take a look at the spec I provided? The first version is based 100% on concepts and mechanisms already used in Ecma262.
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