New Twiddle

components.my-button.js

import Ember from 'ember';

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

components.my-select.js

import Ember from 'ember';

export default Ember.Component.extend({
    actions: {
    selectNumber(data) {
      this.sendAction('setAction', {data});
    }
  }
});

controllers.application.js

import Ember from 'ember';

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

controllers.hello.js

import Ember from 'ember';

export default Ember.Controller.extend({
  show: false,
  
    actions: {
    newAction: function(params) {
      this.set('show', params.data);
    }
  },
  
  isShowingBody: function() {
    console.log(this.get('show'))
        return this.get('show');
  }.property('show'),
});

router.js

import Ember from 'ember';
import config from './config/environment';

const Router = Ember.Router.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
  this.route('hello');
});

export default Router;

routes.hello.js

import Ember from 'ember';

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

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

templates.components.my-button.hbs

{{yield}}
<button>Button</button>

{{#if number}}
You picked: {{number}}
{{/if}}

templates.components.my-select.hbs

{{yield}}
<select onchange={{action "selectNumber" value="target.value"}}>
<option value=1>1</option>
<option value=2>2</option>
<option value=3>3</option>
</select>

templates.hello.hbs

{{my-select setAction="newAction"}}
{{my-button number=this.isShowingBody}}

twiddle.json

{
  "version": "0.10.5",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.8.0",
    "ember-data": "2.8.0",
    "ember-template-compiler": "2.8.0",
    "ember-testing": "2.8.0"
  },
  "addons": {}
}