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Malte UblandClaude Opus 5.5
11c97074e2
A class constructor's `return expr` was evaluated and dropped, so `new C()` answered the constructed instance even where Node answers the returned object (`if (C.instance) return C.instance;` built a second instance). A return that yields an instance of the class itself stores it in a per-class result slot, read and cleared by one helper at every construction site (direct new, class values, the checked dynamic construction dispatchers, record-to-class coercion). A return of any other object refuses with SC1090 (compile time in TypeScript, a deferred fence in JavaScript); a JavaScript value typed only at run time is tested when it returns. super() into a class that can return an existing instance refuses, since Node would rebind the subclass's this. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
16 lines
387 B
TypeScript
16 lines
387 B
TypeScript
// `super()` into a constructor that can return an existing instance would
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// rebind the subclass's `this` to that instance.
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class Shared {
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static one: Shared | undefined = undefined;
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constructor() {
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if (Shared.one) return Shared.one;
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Shared.one = this;
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}
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}
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class Derived extends Shared {
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constructor() {
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super();
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}
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}
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console.log(new Derived() instanceof Derived);
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