progress

Author: ef4

packages/@ember/-internals/metal/lib/cached.ts

@@ -3,6 +3,11 @@
 // of @cached, so any changes made to one should also be made to the other
 import { DEBUG } from '@glimmer/env';
 import { createCache, getValue } from '@glimmer/validator';
+import {
+  type Decorator,
+  identifyModernDecoratorArgs,
+  isModernDecoratorArgs,
+} from './decorator-util';
 
 /**
  * @decorator
@@ -84,7 +89,7 @@ import { createCache, getValue } from '@glimmer/validator';
   the subsequent cache invalidations of the `@cached` properties who were
   using this `trackedProp`.
 
-  Remember that setting tracked data should only be done during initialization, 
+  Remember that setting tracked data should only be done during initialization,
   or as the result of a user action. Setting tracked data during render
   (such as in a getter), is not supported.
 
@@ -94,6 +99,10 @@ import { createCache, getValue } from '@glimmer/validator';
   @public
  */
 export const cached: MethodDecorator = (...args: any[]) => {
+  if (isModernDecoratorArgs(args)) {
+    return cached2023(args) as any;
+  }
+
   const [target, key, descriptor] = args;
 
   // Error on `@cached()`, `@cached(...args)`, and `@cached propName = value;`
@@ -123,6 +132,23 @@ export const cached: MethodDecorator = (...args: any[]) => {
   };
 };
 
+function cached2023(args: Parameters<Decorator>) {
+  const dec = identifyModernDecoratorArgs(args);
+  switch (dec.kind) {
+    case 'getter': {
+      const caches = new WeakMap();
+      return function (this: any) {
+        if (!caches.has(this)) {
+          caches.set(this, createCache(dec.value.bind(this)));
+        }
+        return getValue(caches.get(this));
+      };
+    }
+    default:
+      throw new Error(`unsupported use of @cached on ${dec.kind} ${dec.context.name?.toString()}`);
+  }
+}
+
 function throwCachedExtraneousParens(): never {
   throw new Error(
     'You attempted to use @cached(), which is not necessary nor supported. Remove the parentheses and you will be good to go!'

packages/@ember/-internals/metal/lib/computed.ts

@@ -886,8 +886,11 @@ export function computed(
   ...args: ElementDescriptor | string[] | ComputedDecoratorKeysAndConfig
 ): ComputedDecorator | DecoratorPropertyDescriptor | void {
   if (isModernDecoratorArgs(args)) {
-    console.log(`ignoring computed on ${args[1].kind} ${args[1].name?.toString()}`);
-    return;
+    let decorator = makeComputedDecorator(
+      new ComputedProperty([]),
+      ComputedDecoratorImpl
+    ) as ComputedDecorator;
+    return decorator(...(args as [any, any]));
   }
 
   assert(

packages/@ember/-internals/metal/lib/decorator.ts

@@ -128,7 +128,7 @@ export function makeComputedDecorator(
       string,
       DecoratorPropertyDescriptor | undefined,
       Meta | undefined,
-      boolean | undefined
+      boolean | undefined,
     ];
 
     return makeDescriptor(
@@ -166,7 +166,7 @@ function makeDescriptor(
       !COMPUTED_GETTERS.has(propertyDesc.get)
   );
 
-  let meta = argsLength === 3 ? metaFor(target) : maybeMeta;
+  let meta = argsLength < 4 ? metaFor(target) : maybeMeta;
   desc.setup(target, key, propertyDesc, meta!);
 
   let computedDesc: PropertyDescriptor = {
@@ -190,6 +190,17 @@ function computedDecorator2023(args: Parameters<Decorator>, desc: ComputedDescri
         );
       });
       break;
+    case 'getter':
+      dec.context.addInitializer(function (this: any) {
+        Object.defineProperty(
+          this,
+          dec.context.name,
+          makeDescriptor(desc, 2, this, dec.context.name as string, {
+            get: dec.value as any,
+          })
+        );
+      });
+      break;
     default:
       console.log(
         `unimplemented: computedDecorator on ${dec.kind} ${dec.context.name?.toString()}`