JSONRegistry - Allows branded instances in regular JSON

💡 Ideas
46

another way to solve this, when cyclic special instances are expected, could be this one:

const bars = new WeakMap;

class Foo {
  #bar;

  get bar() {
    return this.#bar;
  }

  initBar(bar) {
    if (this.#bar !== undefined) throw Error();
    this.#bar = bar;
  }

  static isFoo(foo) {
    return #bar in foo;
  }

  static asClonePayload(foo) {
    return foo.#bar.foo === foo ? null : foo.#bar;
  }

  static fromClonePayload(bar) {
    const foo = new Foo;
    if (!bar) {
      bar = new Bar(foo);
      bars.set(foo, bar);
    }
    foo.initBar(bar);
    return foo;
  }
}

class Bar {
  #foo;

  constructor(foo) {
    this.#foo = foo;
  }

  get foo() {
    return this.#foo;
  }

  static isBar(bar) {
    return #foo in bar;
  }

  static asClonePayload(bar) {
    return bar.#foo;
  }

  static fromClonePayload(foo) {
    return bars.get(foo) ?? new Bar(foo);
  }
}

I guess what I am trying to say is that if a user wants to play "seppuku" there are solutions to avoid that but that's a user excercise, it's nothing strictly related to the proposal which can work for most common scenarios (and cycles are not a common scenario, these are rather edge cases 'cause these are throwing in JSON and non-existent in structuredClone due its well known compatible instances that never carry cycles, just cross-reference, eventually).