You are also probably forgetting class methods are non enumerable, and assign works only with enumerable and it copies/assigns retrieved values, not descriptors.
Please let's drop `Object.assign` from the traits discussion already, since it won't work with any ES5+ feature, thanks. On Thu, Feb 12, 2015 at 9:19 PM, Benjamin Gruenbaum <[email protected]> wrote: > Sorry, forgot to CC the list > > *From:* Benjamin Gruenbaum <[email protected]> > *Date:* February 12, 2015 at 22:19:14 GMT+2 > *To:* Domenic Denicola <[email protected]> > *Subject:* *Re: about lightweight traits* > > Those points are good, let me try to address them > > State - In other languages like C# and swift the issue with adding custom > state can be indeed very painful - in JS we can add a symbol on the object > mixed into or lazily creating it when the method first executes with a > default value. A Symbol can be used for separation of state from the object > if that is desired. I don't understand the argument about internal state - > how would a mixin be aware of a class's internal not relating to it state > anyway? > > Protocol - I agree here, but can't you call `.assign` in the constructor? > > On Feb 12, 2015, at 22:11, Domenic Denicola <[email protected]> wrote: > > > From: es-discuss [mailto:[email protected] > <[email protected]>] On Behalf Of Benjamin Gruenbaum > > > We have `Object.assign` that works fantastically for most classic trait > use cases. > > > Well, actually, it works extremely poorly. The old (now dead or deferred) > `Object.mixin`, once called `Object.define`, is a better fit. But it still > fails to account for a couple things, off the top of my head: > > > - Being able to add custom initialization logic to the class constructor > when "mixing in" a trait. You can construct a custom protocol around this, > but (a) that means the class you're mixing in to needs to be aware of the > protocol; (b) everyone needs to agree on a protocol across the ecosystem. > > - Pretty much anything to do with private state doesn't work anymore. > > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > >
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