Concatenated classNameBindings

components.first-component.js

import Ember from 'ember';
import MainComponent from './main-component';

export default MainComponent.extend({
  //classNameBindings: ['_className', '_className'],
  
  _componentClassName: 'first-component',
  
  init() {
    this._super(...arguments);
    this.set('classNameBindings', ['_className']);
    console.log('ClassName: ', this._className);
  },
  
  didReceiveAttrs() {
    this.set('_className', this.generateClassName());
  },
  
  generateClassName() {
   	return this.get('_componentClassName'); 
  }
});

components.main-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  classNameBindings: ['_className'],
  
  _className: 'main-component',
});

components.second-component.js

import Ember from 'ember';
import MainComponent from './main-component';

export default MainComponent.extend({
  classNameBindings: ['_className'],
  
  _className: 'second-component',
});

controllers.application.js

import Ember from 'ember';

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

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

h1 { 
 color: #b284be; 
}

.sister { color: #ddd; }

templates.application.hbs

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

{{#main-component}}Main Component{{/main-component}}
{{#first-component}}First Component{{/first-component}}
{{#second-component}}Second Component{{/second-component}}

<h1>S<span class="sister">ister</span></h1>

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"
  }
}