Typescript: Decorators within mixins

Created on 12 Mar 2017 · 8Comments · Source: microsoft/TypeScript

I wonder if there's any plans to support decorators within mixins?

  type Constructor<T> = { new (...args: any[]): T }

  function Mixin<T extends Constructor<{}>>(Base : T) {
    return class extends Base {
      constructor(...args: any[]) {
        super(...args)
      }

      @decorator
      get y() {
        return this.x + 3
      }
  }

TSC 2.2.1 currently rejects this construction: [Decorators are not valid here]

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Eric-W0

👍1

Most helpful comment

We got into same issues here https://github.com/wc-catalogue/blaze-elements/blob/master/packages/common/mixins.ts#L10

the quickfix is easy just define the mixin class and return it afterwards:

  type Constructor<T> = { new (...args: any[]): T }

  function Mixin<T extends Constructor<{}>>(Base : T) {
    class MixinClass extends Base {
      constructor(...args: any[]) {
        super(...args)
      }

      @decorator
      get y() {
        return this.x + 3
      }
    }

    return MixinClass;
}

Hotell on 12 Mar 2017

👍8 🎉1

All 8 comments

We got into same issues here https://github.com/wc-catalogue/blaze-elements/blob/master/packages/common/mixins.ts#L10

the quickfix is easy just define the mixin class and return it afterwards:

  type Constructor<T> = { new (...args: any[]): T }

  function Mixin<T extends Constructor<{}>>(Base : T) {
    class MixinClass extends Base {
      constructor(...args: any[]) {
        super(...args)
      }

      @decorator
      get y() {
        return this.x + 3
      }
    }

    return MixinClass;
}

Hotell on 12 Mar 2017

👍8 🎉1

Ah, Wonderful!

Thanks!

Eric-W0 on 12 Mar 2017

❤1

Hmm I would rather keep it open to get core team opinion on this cc @RyanCavanaugh @DanielRosenwasser - if it's desing limitation or bug.
What I suggested is just "hotfix" to not get stuck

thx!

Hotell on 12 Mar 2017

True.

Eric-W0 on 12 Mar 2017

See https://github.com/Microsoft/TypeScript/issues/7342