fix(exo): allow richer behaviorMethods

packages/eventual-send/package.json

@@ -18,6 +18,12 @@
     "lint:types": "tsc",
     "lint:eslint": "eslint '**/*.js'"
   },
+  "exports": {
+    "./package.json": "./package.json",
+    ".": "./src/no-shim.js",
+    "./shim.js": "./shim.js",
+    "./utils.js": "./utils.js"
+  },
   "repository": {
     "type": "git",
     "url": "git+https://github.com/endojs/endo.git"

packages/eventual-send/utils.js

@@ -0,0 +1 @@
+export { getMethodNames } from './src/local.js';

packages/exo/package.json

@@ -33,6 +33,7 @@
   },
   "dependencies": {
     "@endo/env-options": "^0.1.4",
+    "@endo/eventual-send": "^0.17.6",
     "@endo/far": "^0.2.22",
     "@endo/pass-style": "^0.1.7",
     "@endo/patterns": "^0.2.6"

packages/exo/src/exo-tools.js

@@ -1,5 +1,6 @@
-import { E, Far } from '@endo/far';
+import { getMethodNames } from '@endo/eventual-send/utils.js';
 import { hasOwnPropertyOf } from '@endo/pass-style';
+import { E, Far } from '@endo/far';
 import {
   listDifference,
   objectMap,
@@ -12,7 +13,6 @@ import {
   getInterfaceGuardPayload,
   getCopyMapEntries,
 } from '@endo/patterns';
-
 import { GET_INTERFACE_GUARD } from './get-interface.js';
 
 /** @typedef {import('@endo/patterns').Method} Method */
@@ -377,21 +377,6 @@ const bindMethod = (
   return method;
 };
 
-/**
- *
- * @template {Record<PropertyKey, CallableFunction>} T
- * @param {T} behaviorMethods
- * @param {InterfaceGuard<{ [M in keyof T]: MethodGuard }>} interfaceGuard
- * @returns {T & import('./get-interface.js').GetInterfaceGuard<T>}
- */
-const withGetInterfaceGuardMethod = (behaviorMethods, interfaceGuard) =>
-  harden({
-    [GET_INTERFACE_GUARD]() {
-      return interfaceGuard;
-    },
-    ...behaviorMethods,
-  });
-
 /**
  * @template {Record<PropertyKey, CallableFunction>} T
  * @param {string} tag
@@ -408,13 +393,20 @@ export const defendPrototype = (
   interfaceGuard = undefined,
 ) => {
   const prototype = {};
-  if (hasOwnPropertyOf(behaviorMethods, 'constructor')) {
-    // By ignoring any method named "constructor", we can use a
+  const methodNames = getMethodNames(behaviorMethods).filter(
+    // By ignoring any method that seems to be a constructor, we can use a
     // class.prototype as a behaviorMethods.
-    const { constructor: _, ...methods } = behaviorMethods;
-    // @ts-expect-error TS misses that hasOwn check makes this safe
-    behaviorMethods = harden(methods);
-  }
+    key => {
+      if (key !== 'constructor') {
+        return true;
+      }
+      const constructor = behaviorMethods.constructor;
+      return !(
+        constructor.prototype &&
+        constructor.prototype.constructor === constructor
+      );
+    },
+  );
   /** @type {Record<PropertyKey, MethodGuard> | undefined} */
   let methodGuards;
   /** @type {import('@endo/patterns').DefaultGuardType} */
@@ -434,8 +426,6 @@ export const defendPrototype = (
     });
     defaultGuards = dg;
     {
-      const methodNames = ownKeys(behaviorMethods);
-      assert(methodGuards);
       const methodGuardNames = ownKeys(methodGuards);
       const unimplemented = listDifference(methodGuardNames, methodNames);
       unimplemented.length === 0 ||
@@ -446,12 +436,9 @@ export const defendPrototype = (
           Fail`methods ${q(unguarded)} not guarded by ${q(interfaceName)}`;
       }
     }
-    behaviorMethods = withGetInterfaceGuardMethod(
-      behaviorMethods,
-      interfaceGuard,
-    );
   }
-  for (const prop of ownKeys(behaviorMethods)) {
+
+  for (const prop of methodNames) {
     prototype[prop] = bindMethod(
       `In ${q(prop)} method of (${tag})`,
       contextProvider,
@@ -463,6 +450,22 @@ export const defendPrototype = (
     );
   }
 
+  if (!hasOwnPropertyOf(prototype, GET_INTERFACE_GUARD)) {
+    const getInterfaceGuardMethod = {
+      [GET_INTERFACE_GUARD]() {
+        // Note: May be `undefined`
+        return interfaceGuard;
+      },
+    }[GET_INTERFACE_GUARD];
+    prototype[GET_INTERFACE_GUARD] = bindMethod(
+      `In ${q(GET_INTERFACE_GUARD)} method of (${tag})`,
+      contextProvider,
+      getInterfaceGuardMethod,
+      thisfulMethods,
+      undefined,
+    );
+  }
+
   return Far(
     tag,
     /** @type {T & import('./get-interface.js').GetInterfaceGuard<T>} */ (

packages/exo/src/get-interface.js

@@ -4,19 +4,23 @@
  * The name of the automatically added default meta-method for
  * obtaining an exo's interface, if it has one.
  *
+ * Intended to be similar to `GET_METHOD_NAMES` from `@endo/pass-style`.
+ *
  * TODO Name to be bikeshed. Perhaps even whether it is a
- * string or symbol to be bikeshed.
+ * string or symbol to be bikeshed. See
+ * https://github.com/endojs/endo/pull/1809#discussion_r1388052454
  *
  * TODO Beware that an exo's interface can change across an upgrade,
  * so remotes that cache it can become stale.
  */
-export const GET_INTERFACE_GUARD = Symbol.for('getInterfaceGuard');
+export const GET_INTERFACE_GUARD = '__getInterfaceGuard__';
 
 /**
  * @template {Record<PropertyKey, CallableFunction>} M
  * @typedef {{
- *   [GET_INTERFACE_GUARD]: () => import('@endo/patterns').InterfaceGuard<{
- *     [K in keyof M]: import('@endo/patterns').MethodGuard
- *   }>
+ *   [GET_INTERFACE_GUARD]: () =>
+ *     import('@endo/patterns').InterfaceGuard<{
+ *       [K in keyof M]: import('@endo/patterns').MethodGuard
+ *     }> | undefined
  * }} GetInterfaceGuard
  */

packages/exo/test/test-exo-class-js-class.js

@@ -0,0 +1,77 @@
+/* eslint-disable max-classes-per-file */
+/* eslint-disable class-methods-use-this */
+// eslint-disable-next-line import/order
+import { test } from './prepare-test-env-ava.js';
+
+import { passStyleOf } from '@endo/pass-style';
+import { M, getInterfaceGuardPayload } from '@endo/patterns';
+import { makeExo, defineExoClass } from '../src/exo-makers.js';
+
+// Based on FarSubclass1 in test-far-class-instances.js
+class DoublerBehaviorClass {
+  double(x) {
+    return x + x;
+  }
+}
+
+const DoublerI = M.interface('Doubler', {
+  double: M.call(M.lte(10)).returns(M.number()),
+});
+
+const doubler = makeExo('doubler', DoublerI, DoublerBehaviorClass.prototype);
+
+test('exo doubler using js classes', t => {
+  t.is(passStyleOf(doubler), 'remotable');
+  t.is(doubler.double(3), 6);
+  t.throws(() => doubler.double('x'), {
+    message: 'In "double" method of (doubler): arg 0: "x" - Must be <= 10',
+  });
+  t.throws(() => doubler.double(), {
+    message:
+      'In "double" method of (doubler): Expected at least 1 arguments: []',
+  });
+  t.throws(() => doubler.double(12), {
+    message: 'In "double" method of (doubler): arg 0: 12 - Must be <= 10',
+  });
+});
+
+// Based on FarSubclass2 in test-far-class-instances.js
+class DoubleAdderBehaviorClass extends DoublerBehaviorClass {
+  doubleAddSelfCall(x) {
+    const {
+      state: { y },
+      self,
+    } = this;
+    return self.double(x) + y;
+  }
+
+  doubleAddSuperCall(x) {
+    const {
+      state: { y },
+    } = this;
+    return super.double(x) + y;
+  }
+}
+
+const DoubleAdderI = M.interface('DoubleAdder', {
+  ...getInterfaceGuardPayload(DoublerI).methodGuards,
+  doubleAddSelfCall: M.call(M.number()).returns(M.number()),
+  doubleAddSuperCall: M.call(M.number()).returns(M.number()),
+});
+
+const makeDoubleAdder = defineExoClass(
+  'doubleAdderClass',
+  DoubleAdderI,
+  y => ({ y }),
+  DoubleAdderBehaviorClass.prototype,
+);
+
+test('exo inheritance self vs super call', t => {
+  const da = makeDoubleAdder(5);
+  t.is(da.doubleAddSelfCall(3), 11);
+  t.throws(() => da.doubleAddSelfCall(12), {
+    message:
+      'In "double" method of (doubleAdderClass): arg 0: 12 - Must be <= 10',
+  });
+  t.is(da.doubleAddSuperCall(12), 29);
+});