chore: more concise durable example

snippets/zoe/src/02b-state-durable.js

@@ -1,31 +1,39 @@
 // @ts-check
-import { makeDurableZone } from '@agoric/zone/durable.js';
+// #region contract
 import { M } from '@endo/patterns';
+// #region import-provide-zone
+import { makeDurableZone } from '@agoric/zone/durable.js';
+import { provide } from '@agoric/vat-data';
+// #endregion import-provide-zone
+
+// #region interface-guard
+const CellI = M.interface('ValueCell', {
+  get: M.call().returns(M.number()),
+  set: M.call(M.number()).returns(),
+});
+// #endregion interface-guard
 
-export const start = (_zcf, _privateArgs, baggage) => {
-  /** @type {import('@agoric/zone').Zone} */
+// #region export-prepare
+export const prepare = (_zcf, _privateArgs, baggage) => {
+  // #endregion export-prepare
+  // #region exo
   const zone = makeDurableZone(baggage);
 
-  const makeCell = zone.exoClass(
-    'Cell',
-    M.interface('Cell', {
-      get: M.call().returns(M.scalar()),
-      set: M.call(M.scalar()).returns(),
-    }),
-    () => ({
-      /** @type {string|number} */
-      value: 'Hello, World!',
-    }),
-    {
-      get() {
-        return this.state.value;
-      },
-      /** @param {string|number} v */
-      set(v) {
-        this.state.value = v;
-      },
+  const makeCell = zone.exoClass('ValueCell', CellI, () => ({ value: 0 }), {
+    get() {
+      return this.state.value;
     },
-  );
-  const publicFacet = makeCell();
+    /** @param {number} v */
+    set(v) {
+      this.state.value = v;
+    },
+  });
+  // #endregion exo
+
+  // #region provide-cell
+  const publicFacet = provide(baggage, 'publicFacet', makeCell);
+
   return { publicFacet };
+  // #endregion provide-cell
 };
+// #endregion contract