Please extend polymorphic this support to static methods as well

[rp-pedraza]

🔍 Search Terms

static polymorphic this

✅ Viability Checklist

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
• This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals

⭐ Suggestion

Basically allow 'this' return type to be applied to static class methods as well.

📃 Motivating Example

class Singleton {
  constructor() {
    if (this.constructor.name === 'Singleton') {
      throw new Error("Can't instantiate the Singleton class directly")
    }

    const subclass = this.constructor as { __singleton_instance?: object }

    if (subclass.__singleton_instance) {
      throw new Error("Class can only be instantiated once")
    }

    subclass.__singleton_instance = this
  }

  public static get instance(): this {
    return (this as { __singleton_instance?: object }).__singleton_instance ?? new this()
  }
}

class SomeObject extends Singleton {} // No wrapper "get instance" method that explicitly returns SomeObject needed

💻 Use Cases

As mentioned above.

[rp-pedraza]

And it would be nice to be able to specify this in local castings as well:

    return (this as { __singleton_instance?: this }).__singleton_instance ?? new this()

[MartinJohns]

Duplicate of #5863. Used search terms: this static in:title

[rp-pedraza]

Closing as duplicate