FEATURE: support for mixin/trait (by language new keyword)

[kamil-kielczewski]

TypeScript Version: 2.4.0 / nightly (2.5.0-dev.201xxxxx)

Code

In typescript documentation about mixins is described that typescript support mixins/traits - this is in fact not true because programmer need implements everything himself - so where is support?.

Proper support for mixin should be by language KEYWORD like mixin or trait & use (like in php). And programer should use it in this way (without double mixin methods definition stub):

class SmartObject mixin Disposable, Activatable {
    constructor() {
        setInterval(() => console.log(this.isActive + " : " + this.isDisposed), 500);
    }

    interact() {
        this.activate();
    }
}

(i use example context from documentation for which link I give above)

And thats all! Any rendundant mehtod/fields deinition shouldn't be inside class SmartObject and also any applyMixins should not be written by TS programmer. If we will achieve this, then we can say that TS support mixins/traits.

Expected behavior:

Look description above

Actual behavior:

Look description above

Duplicate of #7798 and #2919.
See TypeScript's design goals. Specifically: Avoid adding expression-level syntax. (This would presumably affect class expressions.)

[mhegazy]

Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.