<https://facebook.github.io/react/blog/2016/07/13/mixins-considered-harmful.html> <https://facebook.github.io/react/blog/2016/07/13/mixins-considered-harmful.html> https://facebook.github.io/react/blog/2016/07/13/mixins-considered-harmful.html may also be a helpful read.
(fwiw, any Symbol to modify property lookup would not likely ship before Proxy was available, so "use Proxy" is a pretty solid suggestion for this) On Wed, Jul 13, 2016 at 1:04 PM, /#!/JoePea <[email protected]> wrote: > Thanks kdex. > > In one of my cases, `A` extends `B` extends `C` just so that `A` can have > characteristics of both `B` and `C`, but it doesn't actually make sense for > `B` to extend `C` because `B` is not a more specific form of `C` -- `B` and > `C` are completely unrelated classes; I'm extending `B` from `C` just for > `A` to have both sets of characteristics. > > How might decorators be used instead? > > I found some good reading: > > - > https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes#Mix-ins > - http://justinfagnani.com/2015/12/21/real-mixins-with-javascript-classes/ > > I am currently reading to get ideas on what I might do, but would love > suggestions if you have any. > > */#!/*JoePea > > On Wed, Jul 13, 2016 at 3:00 AM, kdex <[email protected]> wrote: > >> Callable class constructors [1] have been discussed at some point. >> They've been withdrawn [2] in favor of decorators [3], though. >> >> [1] >> https://github.com/tc39/ecma262/blob/master/workingdocs/callconstructor.md >> [2] >> https://github.com/tc39/proposals/blob/master/inactive-proposals.md#inactive-proposals >> [3] https://github.com/wycats/javascript-decorators/blob/master/README.md >> >> On Wednesday, July 13, 2016 2:24:10 AM CEST /#!/JoePea wrote: >> > Oops, I forgot that ES6 classes can't be called using the >> > `SomeClass.call(...)` form. Is there a workaround for that so that my >> > constructor can call all of them (besides downgrading to ES5 classes)? >> > >> > ```js >> > class Foo extends new MultiClass(One, Two) { >> > constructor(...args) { >> > One.call(this, ...args) >> > // Error, not allowed >> > >> > >> > Two >> > .call(this, ...args) // >> > Error >> > , not allowed >> > >> > } >> > } >> > ``` >> > >> > */#!/*JoePea >> > >> > On Wed, Jul 13, 2016 at 1:49 AM, /#!/JoePea <[email protected]> wrote: >> > >> > > Thanks guys, Proxy is the one, but not supported natively enough yet >> > > unfortunately. >> > > >> > > Here is the ES5 solution I came up with, which creates "proxy" >> methods on >> > > the "multiPrototype" of the new MultiClass: >> > > >> > > ```js >> > > class MultiClass { >> > > constructor(...constructors) { >> > > let constructorName = '' >> > > let multiPrototype = {} >> > > >> > > console.log(' -- Creating new MultiClass.') >> > > >> > > for (let i=0, l=constructors.length; i<l; i+=1) { >> > > const constructor = constructors[i] >> > > >> > > constructorName += constructor.name + (i == l-1 ? '' : >> '+') >> > > // f.e. SomeClass_OtherClass_FooBar >> > > >> > > let props = >> > > >> SimplePropertyRetriever.getOwnAndPrototypeEnumerablesAndNonenumerables(constructor.prototype) >> > > for (let prop of props) { >> > > multiPrototype[prop] = constructor.prototype[prop] >> > > console.log(' --- prop', prop) >> > > } >> > > } >> > > >> > > // temporary object to store the new MultiClass constructor, >> > > because >> > > // using an object allows us to programmatically assign a >> name to >> > > the >> > > // function, which we otherwise cannot do without eval(). >> > > let tmp = { >> > > >> > > // This new constructor doesn't do much, just has all the >> given >> > > // constructor prototypes mixed in to it's own prototype. >> Be >> > > sure to >> > > // call the each constructor manually in the class that >> > > extends this >> > > // new MultiClass. >> > > [constructorName]() {} >> > > >> > > } >> > > >> > > tmp[constructorName].prototype = multiPrototype >> > > >> > > return tmp[constructorName] >> > > } >> > > } >> > > ``` >> > > >> > > Where `SimplePropertyRetriever` is taken from the MDN article >> > > [Enumerability and ownership of properties]( >> > > >> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Enumerability_and_ownership_of_properties#Obtaining_properties_by_enumerabilityownership >> > > ). >> > > >> > > Example usage: >> > > >> > > ```js >> > > class One { >> > > foo() {console.log('foo')} >> > > } >> > > >> > > class Two { >> > > constructor() {/* ... */} >> > > bar() {console.log('bar')} >> > > } >> > > >> > > class Three extends Two { >> > > constructor(...args) { >> > > super(...args) >> > > // ... >> > > } >> > > baz() {console.log('baz')} >> > > } >> > > >> > > class FooBar extends new MultiClass(Three, One) { >> > > constructor(...args) { >> > > super() // needed, although does nothing. >> > > >> > > // call each constructor. >> > > One.call(this, ...args) >> > > Three.call(this, ...args) >> > > } >> > > oh() {console.log('oh')} >> > > yeah() {console.log('yeah')} >> > > } >> > > >> > > let f = new FooBar >> > > >> > > f.foo() >> > > f.bar() >> > > f.baz() >> > > f.oh() >> > > f.yeah() >> > > ``` >> > > >> > > Any ideas on how else to do it? >> > > >> > > */#!/*JoePea >> > > >> > > On Tue, Jul 12, 2016 at 1:52 AM, Claude Pache <[email protected] >> > >> > > wrote: >> > > >> > >> >> > >> Le 12 juil. 2016 à 02:45, /#!/JoePea <[email protected]> a écrit : >> > >> >> > >> Does one exist? I'm imagining an implementation for >> > >> >> > >> ``` >> > >> class Node extends new MultiClass(ImperativeBase, Transformable) { >> > >> } >> > >> ``` >> > >> >> > >> >> > >> I think that Proxy is the tool for that purpose. >> > >> >> > >> How a symbol would work here, since you need a property lookup in >> order >> > >> to find that symbol? >> > >> >> > >> —Claude >> > >> >> > > >> > > >> > >> > > > _______________________________________________ > 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
