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 They've been withdrawn [2] in favor of decorators [3], though.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
