feat(pass-style): Far GET_METHOD_NAMES meta method

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/src/exo-tools.js

@@ -1,4 +1,4 @@
-import { getMethodNames } from '@endo/eventual-send/src/local.js';
+import { getMethodNames } from '@endo/eventual-send/utils.js';
 import { E, Far } from '@endo/far';
 import {
   listDifference,
@@ -13,6 +13,7 @@ import {
   getCopyMapEntries,
 } from '@endo/patterns';
 import { GET_INTERFACE_GUARD } from './get-interface.js';
+import { hasOwnPropertyOf } from '@endo/pass-style';
 
 /** @typedef {import('@endo/patterns').Method} Method */
 /** @typedef {import('@endo/patterns').MethodGuard} MethodGuard */
@@ -426,18 +427,20 @@ export const defendPrototype = (
     );
   }
 
-  const getInterfaceGuardMethod = {
-    [GET_INTERFACE_GUARD]() {
-      return interfaceGuard;
-    },
-  }[GET_INTERFACE_GUARD];
-  prototype[GET_INTERFACE_GUARD] = bindMethod(
-    `In ${q(GET_INTERFACE_GUARD)} method of (${tag})`,
-    contextProvider,
-    getInterfaceGuardMethod,
-    thisfulMethods,
-    undefined,
-  );
+  if (interfaceGuard && !hasOwnPropertyOf(prototype, GET_INTERFACE_GUARD)) {
+    const getInterfaceGuardMethod = {
+      [GET_INTERFACE_GUARD]() {
+        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,

packages/exo/src/get-interface.js

@@ -18,6 +18,6 @@ export const GET_INTERFACE_GUARD = Symbol.for('getInterfaceGuard');
  *   [GET_INTERFACE_GUARD]: () =>
  *     import('@endo/patterns').InterfaceGuard<{
  *       [K in keyof M]: import('@endo/patterns').MethodGuard
- *     }> | undefined
+ *     }>
  * }} GetInterfaceGuard
  */

packages/exo/test/test-exo-wobbly-point.js

@@ -10,10 +10,9 @@
 /* eslint-disable-next-line import/order */
 import { test } from './prepare-test-env-ava.js';
 
-// TODO enable import of getMethodNames without deep import
 // eslint-disable-next-line import/order
-import { getMethodNames } from '@endo/eventual-send/src/local.js';
-import { passStyleOf, Far } from '@endo/pass-style';
+import { getMethodNames } from '@endo/eventual-send/utils.js';
+import { passStyleOf, Far, GET_METHOD_NAMES } from '@endo/pass-style';
 import { M } from '@endo/patterns';
 import { defineExoClass } from '../src/exo-makers.js';
 import { GET_INTERFACE_GUARD } from '../src/get-interface.js';
@@ -102,6 +101,7 @@ test('ExoPoint instances', t => {
   t.false(pt instanceof ExoPoint);
   t.deepEqual(getMethodNames(pt), [
     GET_INTERFACE_GUARD,
+    GET_METHOD_NAMES,
     'getX',
     'getY',
     'setY',
@@ -154,6 +154,7 @@ test('FarWobblyPoint inheritance', t => {
   t.is(passStyleOf(wpt), 'remotable');
   t.deepEqual(getMethodNames(wpt), [
     GET_INTERFACE_GUARD,
+    GET_METHOD_NAMES,
     'getX',
     'getY',
     'setY',

packages/exo/test/test-heap-classes.js

@@ -172,7 +172,9 @@ test('missing interface', t => {
     message:
       'In "makeSayHello" method of (greeterMaker): result: "[Symbol(passStyle)]" property expected: "[Function <anon>]"',
   });
-  t.is(greeterMaker[GET_INTERFACE_GUARD](), undefined);
+  t.throws(() => greeterMaker[GET_INTERFACE_GUARD](), {
+    message: 'greeterMaker[GET_INTERFACE_GUARD] is not a function',
+  });
 });
 
 const SloppyGreeterI = M.interface('greeter', {}, { sloppy: true });

packages/pass-style/index.js

@@ -24,7 +24,12 @@ export {
 export { passStyleOf, assertPassable } from './src/passStyleOf.js';
 
 export { makeTagged } from './src/makeTagged.js';
-export { Remotable, Far, ToFarFunction } from './src/make-far.js';
+export {
+  Remotable,
+  Far,
+  ToFarFunction,
+  GET_METHOD_NAMES,
+} from './src/make-far.js';
 
 export {
   assertRecord,

packages/pass-style/package.json

@@ -33,6 +33,7 @@
     "test": "ava"
   },
   "dependencies": {
+    "@endo/eventual-send": "^0.17.6",
     "@endo/promise-kit": "^0.2.60",
     "@fast-check/ava": "^1.1.5"
   },

packages/pass-style/src/make-far.js

@@ -1,5 +1,6 @@
 /// <reference types="ses"/>
 
+import { getMethodNames } from '@endo/eventual-send/utils.js';
 import { assertChecker, PASS_STYLE } from './passStyle-helpers.js';
 import { assertIface, getInterfaceOf, RemotableHelper } from './remotable.js';
 
@@ -128,16 +129,57 @@ export const Remotable = (
 };
 harden(Remotable);
 
+/**
+ * The name of the automatically added default meta-method for obtaining a
+ * list of all methods of an object declared with `Far`, or an object that
+ * inherits from an object declared with `Far`.
+ *
+ * Modeled on `GET_INTERFACE_GUARD` from
+ *
+ * TODO Name to be bikeshed. Perhaps even whether it is a
+ * string or symbol to be bikeshed.
+ *
+ * TODO Beware that an exo's interface can change across an upgrade,
+ * so remotes that cache it can become stale.
+ */
+export const GET_METHOD_NAMES = Symbol.for('getMethodNames');
+
+/**
+ * Note that the returned method is a thisful method! It must be so that
+ * it works as expected with far-object inheritance.
+ *
+ * @returns {(string|symbol)[]}
+ */
+const getMethodNamesMethod = harden({
+  [GET_METHOD_NAMES]() {
+    getMethodNames(this);
+  },
+})[GET_METHOD_NAMES];
+
 /**
  * A concise convenience for the most common `Remotable` use.
  *
+ * For far objects (as opposed to far functions), also adds a miranda
+ * `GET_METHOD_NAMES` method that returns an array of all the method names,
+ * if there is not yet any method named `GET_METHOD_NAMES`. (Hence "miranda")
+ *
  * @template {{}} T
  * @param {string} farName This name will be prepended with `Alleged: `
  * for now to form the `Remotable` `iface` argument.
  * @param {T} [remotable] The object used as the remotable
  */
 export const Far = (farName, remotable = undefined) => {
   const r = remotable === undefined ? /** @type {T} */ ({}) : remotable;
+  if (typeof r === 'object' && !(GET_METHOD_NAMES in r)) {
+    // This test excludes far functions, since we currently consider them
+    // to only have a call-behavior, with no callable methods.
+    // Beware: Mutates the input argument! But `Remotable`
+    // * requires the object to be mutable
+    // * does further mutations,
+    // * hardens the mutated object before returning it.
+    // so this mutation is not unprecedented. But it is surprising!
+    r[GET_METHOD_NAMES] = getMethodNamesMethod;
+  }
   return Remotable(`Alleged: ${farName}`, undefined, r);
 };
 harden(Far);

packages/pass-style/test/test-far-class-instances.js

@@ -2,11 +2,10 @@
 /* eslint-disable max-classes-per-file */
 import { test } from './prepare-test-env-ava.js';
 
-// TODO enable import of getMethodNames without deep import
 // eslint-disable-next-line import/order
-import { getMethodNames } from '@endo/eventual-send/src/local.js';
+import { getMethodNames } from '@endo/eventual-send/utils.js';
 import { passStyleOf } from '../src/passStyleOf.js';
-import { Far } from '../src/make-far.js';
+import { Far, GET_METHOD_NAMES } from '../src/make-far.js';
 
 /**
  * Classes whose instances should be Far objects may find it convenient to
@@ -48,7 +47,7 @@ class FarSubclass2 extends FarSubclass1 {
 test('far class instances', t => {
   const fb = new FarBaseClass();
   t.is(passStyleOf(fb), 'remotable');
-  t.deepEqual(getMethodNames(fb), ['constructor']);
+  t.deepEqual(getMethodNames(fb), [GET_METHOD_NAMES, 'constructor']);
 
   t.assert(new fb.constructor() instanceof FarBaseClass);
   t.throws(() => fb.constructor(), {
@@ -60,13 +59,18 @@ test('far class instances', t => {
   t.is(passStyleOf(fs1), 'remotable');
   t.is(fs1.double(4), 8);
   t.assert(new fs1.constructor() instanceof FarSubclass1);
-  t.deepEqual(getMethodNames(fs1), ['constructor', 'double']);
+  t.deepEqual(getMethodNames(fs1), [GET_METHOD_NAMES, 'constructor', 'double']);
 
   const fs2 = new FarSubclass2(3);
   t.is(passStyleOf(fs2), 'remotable');
   t.is(fs2.double(4), 8);
   t.is(fs2.doubleAdd(4), 11);
-  t.deepEqual(getMethodNames(fs2), ['constructor', 'double', 'doubleAdd']);
+  t.deepEqual(getMethodNames(fs2), [
+    GET_METHOD_NAMES,
+    'constructor',
+    'double',
+    'doubleAdd',
+  ]);
 
   const yField = new WeakMap();
   class FarSubclass3 extends FarSubclass1 {
@@ -84,7 +88,12 @@ test('far class instances', t => {
   t.is(passStyleOf(fs3), 'remotable');
   t.is(fs3.double(4), 8);
   t.is(fs3.doubleAdd(4), 11);
-  t.deepEqual(getMethodNames(fs3), ['constructor', 'double', 'doubleAdd']);
+  t.deepEqual(getMethodNames(fs3), [
+    GET_METHOD_NAMES,
+    'constructor',
+    'double',
+    'doubleAdd',
+  ]);
 });
 
 test('far class instance hardened empty', t => {

packages/pass-style/test/test-far-wobbly-point.js

@@ -7,11 +7,10 @@
 /* eslint-disable max-classes-per-file */
 import { test } from './prepare-test-env-ava.js';
 
-// TODO enable import of getMethodNames without deep import
 // eslint-disable-next-line import/order
-import { getMethodNames } from '@endo/eventual-send/src/local.js';
+import { getMethodNames } from '@endo/eventual-send/utils.js';
 import { passStyleOf } from '../src/passStyleOf.js';
-import { Far } from '../src/make-far.js';
+import { Far, GET_METHOD_NAMES } from '../src/make-far.js';
 
 const { apply } = Reflect;
 
@@ -66,6 +65,7 @@ test('FarPoint instances', t => {
   t.is(passStyleOf(pt), 'remotable');
   t.assert(pt instanceof FarPoint);
   t.deepEqual(getMethodNames(pt), [
+    GET_METHOD_NAMES,
     'constructor',
     'getX',
     'getY',
@@ -104,6 +104,7 @@ test('FarWobblyPoint inheritance', t => {
   t.assert(wpt instanceof FarPoint);
   t.is(passStyleOf(wpt), 'remotable');
   t.deepEqual(getMethodNames(wpt), [
+    GET_METHOD_NAMES,
     'constructor',
     'getX',
     'getY',