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Author: erights

no-stamping-talks/global-com-channel.js

@@ -0,0 +1,24 @@
+class ReturnOverrideClass {
+  constructor(key) { return key; }
+}
+
+class HiddenWeakMap extends ReturnOverrideClass {
+  #value;
+
+  constructor(key, value) {
+    super(key);
+    this.#value = value;
+  }
+
+  static get(hwm) {
+    return hwn.#value;
+  }
+}
+harden(HiddenWeakMap);
+
+// HardenedJS builtins all frozen
+new HiddenWeakMap(Object, Date);
+
+// in separate compartment
+HiddenWeakMap.get(Object); // Date or not.
+// Where's the mutability?

no-stamping-talks/hidden-weak-map.js

@@ -0,0 +1,40 @@
+class Trojan {
+  constructor(key) {
+    return key;
+  }
+}
+
+const makeHiddenWeakMap = () => {
+  const tombstone = Symbol('deleted');
+  class PrivateTagger extends Trojan {
+    #value;
+    constructor(key, value) {
+      super(key);
+      this.#value = value;
+    }
+
+    static HiddenWeakMap = class {
+      set(key, value) { new PrivateTagger(key, value); }
+
+      has(key) {
+        try {
+          return key.#value !== tombstone;
+        } catch { return false; }
+      }
+      get(key) {
+        try {
+          const value = key.#value;
+          return value === tombstone ? undefined : value;
+        } catch { return undefined; }
+      }
+      delete(key) {
+        if (this.has(key)) {
+          key.#value = tombstone;
+          return true;
+        }
+        return false;
+      }
+    }
+  };
+  return PrivateTagger.HiddenWeakMap;
+}

no-stamping-talks/mitigate-return-override.js

@@ -0,0 +1,15 @@
+class Trojan {
+  constructor(key) { return key; }
+}
+
+class Tagger extends Trojan {
+  #value;
+
+  constructor(key, value) {
+    super(key);
+    this.#value = value;
+  }
+}
+
+// struct instances born sealed
+new Tagger(struct, 'a'); // adds #value to struct anyway

no-stamping-talks/non-extensible-applies-to-private.key

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+class NonExtensibleBase {
+  constructor() {
+    Object.preventExtensions(this);
+  }
+}
+
+class ClassWithPrivateField
+                    extends NonExtensibleBase {
+  #val;
+
+  constructor(v) {
+    super();
+    this.#val = v;
+  }
+}
+
+new ClassWithPrivateField(42); // doesn't throw

no-stamping-talks/non-extensible-applies-to-private.pdf

@@ -0,0 +1,29 @@
+class FrozenBase {
+  constructor() {
+    Object.freeze(this);
+  }
+}
+
+class AddsProperty extends FrozenBase {
+  _val;
+
+  constructor(v) {
+    super();
+    this._val = v;
+  }
+}
+
+// throws TypeError
+new AddsProperty(42);
+
+class AddsPrivateField extends FrozenBase {
+  #val;
+
+  constructor(v) {
+    super();
+    this.#val = v;
+  }
+}
+
+// doesn’t throw
+new AddsPrivateField(42);