> Le 6 févr. 2015 à 05:47, Luke Scott <[email protected]> a écrit : > > I know traits are not something that will make it into ES6. This was the > suggested alternative on the mailing list: > > class Thing extends mixin(Base, Trait1, Trait2) {...} > > Unfortuantly since rev32 this is now seems impossible, as a custom > implementation of traits would need to this to work: > > class Foo { > constructor() {} > } > function ctor() { > Foo.call(this); // <— illegal? > } > ctor.prototype = Object.create(Foo.prototype); > ctor.prototype.constructor = ctor; > new ctor();
That pattern is the exact (almost character-for-character) pattern I use for defining a subclass the pre-ES6 way. Thus, (as you noted in a subsequent message,) just use standard ES6 subclassing, (but beware of enumerability issues). But, more generally, that raises an interesting issue if you intend to write a general library that works both with ES6-classes and pre-ES6-pseudoclasses: If you use the pre-ES6 pattern, it risks to break on ES6-classes; but if you use the ES6-classes pattern, it will (fortunately) probably work with pre-ES6-pseudoclasses, but it won't compile on implementations that don't support ES6-classes. So, you have to write your library the both ways and do some feature-detection in order to decide what code to serve. —Claude > > The code I’m working with makes extensive use of traits. Simple inheritance > just doesn’t work for what I’m trying to do (and avoid duplicating code). I’m > using 6to5, and now Trait.call(this) is failing since I was defining my > traits as classes. I can fix this by not using classes for my traits, and > 6to5 or traceur cannot enforce Foo.call(this) from being illegal since “this > instanceof Foo” is true, but it is sure to break on the real thing. > > Hopefully I’m wrong in that Foo.call(this) is illegal, but if it is, this is > a devastating change, especially when traits are scheduled for ES7 or later. > > -- > Luke > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
