New Twiddle

controllers.application\.js

import Controller from '@ember/controller';
import Ember from 'ember';

function foo(target, name, descriptor) {
  console.log('foo', target, name, descriptor);

  console.log(  descriptor.initializer);
  
  Object.defineProperty(target, name, {
    configurable: false,
    get() {
      console.log('foo getter');
      return `Yes ${name}`;
    }
  });
}

function bar(blah) {
  console.log('bar decorator', arguments);
  return function(target, name, descriptor) {
  	console.log('bar', target, this, name, descriptor);
    return {
      get() {
      console.log('bar getter');
        return `Yes ${name} ${blah}`;
      }
    };
  }

}

function blah(arg) {
  return `Hello ${arg}`;
}

export default class ApplicationController extends Controller {
  appName = 'Ember Twiddle';
  @foo foo = blah('123');
  @bar('123') bar;
	get bazz() {
    console.log('baz', this);
  }
}

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
<br>
foo: {{this.foo}}
<br>
bar: {{bar}}
<br>
<br>

twiddle\.json

{
  "version": "0.17.1",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.18.1",
    "ember-template-compiler": "3.18.1",
    "ember-testing": "3.18.1"
  },
  "addons": {
    "@glimmer/component": "1.0.0"
  }
}