New Twiddle

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
});

components.x-foo.js

import Ember from 'ember';

export default Ember.Component.extend({
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{#my-component as |xfoo|}}
  {{#xfoo}}
    Block passed to xfoo contextual component
  {{/xfoo}}
{{/my-component}}
<br>
<br>

templates.components.my-component.hbs

begin myComponent <br>
{{yield (component 'x-foo')}}
end myComponent <br>

templates.components.x-foo.hbs

begin x-foo <br>
{{yield}}
end x-foo <br>

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}