app/computed-property-macros/hash.js

controller.js

import Ember from 'ember';
import hash from 'app/computed-property-macros/hash';

const {
  Component
} = Ember;

export default Component.extend({
  order: hash('price', 'count')
});

hash.js

import Ember from 'ember';

const {
  computed,
  get
} = Ember;

export default function(...props) {
  return computed(...props, function(){
    let result = {};
    props.forEach((prop) => {
      result[prop] = get(this, prop);
    });
    return result;
  });
}

template.hbs

<label>Price: {{input value=price}}</label>
<label>Count: {{input value=count}}</label>