Add a new type PublicOf

Suggestion

Add the PublicOf type suggested in this issue's comment by @DanielRosenwasser

Use Cases

Implement a class public properties/methods without the need to implement private/protected ones.

Examples

// type to add
type PublicOf<T> = {
    [P in keyof T]: T[P]
}

// use case
class C {
    private foo();

    public bar();
}

// No need to implement private method foo !
class D implements PublicOf<C> {
    public bar() {}
}

Checklist

My suggestion meets these guidelines:

• 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, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

Inizia esaminando la proposta collegata e gli esempi presenti in questa issue, quindi analizza come TypeScript gestisce attualmente i mapped types, keyof e i controlli di implements. L’implementazione deve includere un tipo PublicOf supportato, il cui utilizzo consenta alla classe D di implementare i membri pubblici di C senza implementare i membri private o protected, con un’adeguata copertura dei controlli di tipo.