strange dynamic property names

controllers.application.js

import Ember from 'ember';

const {get,set} = Ember;

export default Ember.Controller.extend({
 actions: {
   generate() {
     get(this, 'model').forEach((post, idx) => {
       set(this, 'pst'+idx, post);
     });
     
     set(this, 'ready', true);
   }
 }
});

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  model() {
    return ['foo', 'bar', 'foobar'];
  }
});

templates.application.hbs

bla
<button {{action "generate"}}>generate</button>
<br>

{{#if ready}}

{{#each model as |pst idx|}}
    {{input value=(get this (concat 'pst' idx))}}
{{/each}}

{{/if}}

twiddle.json

{
  "version": "0.7.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.4.3/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.4.3/ember-template-compiler.js"
  }
}