Suggestion: Class friendships

[markvandenbrink]

Are there any plans to incorporate the friend keyword in TypeScript to allow class friendships and improve class encapsulation? I know (real) mixins and abstract classes are on the roadmap for 2.0. But friend classes would be practical as well...

A friend class should have access to the private and protected members of the class in which it is declared as a friend. For example:

class A friend B {
    private Message: string = "hello";
}

class B {
    private Message: string = "there";

    public Greeter(a: A): string {
        return a.Message + " " + this.Message;
    }
}

[danquirk]

We haven't heard many other requests for this. We only recently added protected and there've been a fair number of asks for something like C#'s internal both of which are a lot more common in usage than friend. I wouldn't say we're likely to add this, certainly not in the near term unless there're some very compelling use cases that mesh with existing popular libraries.

[mhegazy]

marking as revisit. as @danquirk mentioned, #5228 is a better alternative here.