.set()ing on init() hook overrides attrs

application.controller.js

import Ember from 'ember';

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

application.template.hbs

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

<p>
	Setting instance level property "defaults" on the
  <code>init()</code> hook overrides the incoming 
  attribute value.
</p>

<h3><code>&#123;&#123;my-foobar&#125;&#125;</code></h3>
{{my-foobar}}

<h3><code>&#123;&#123;my-foobar someAttr="baz" workingAttr="baz"&#125;&#125;</code></h3>
{{my-foobar someAttr="baz" workingAttr="baz"}}

my-foobar.component.js

import Ember from 'ember';

export default Ember.Component.extend({
  tagName: 'p',
  init() {
    this._super(...arguments);
  	this.set('someAttr', 'default');
    // solution by rwjblue
    if ( !('workingAttr' in this) ) {
      this.set('workingAttr', 'default');
    }
    // or (but this won't work for falsy values)
    // this.workingAttr = this.workingAttr || 'default';
    // ^ which is more performant but like
    // this.set(
    //   'workingAttr',
    //   this.getWithDefault('workingAttr', 'default')
    // );
  }
});

my-foobar.template.hbs

<strong>someAttr:</strong>
{{someAttr}}

<br />

<strong>workingAttr:</strong>
{{workingAttr}}

twiddle.json

{
  "version": "0.5.3",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.3.1/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.3.3/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.2.0/ember-template-compiler.js"
  }
}