ComputedProperty#property()

Sets the dependent keys on this computed property. Pass any number of arguments containing key paths that this computed property depends on.

let President = Ember.Object.extend({
  fullName: Ember.computed(function() {
    return this.get('firstName') + ' ' + this.get('lastName');

    // Tell Ember that this computed property depends on firstName
    // and lastName
  }).property('firstName', 'lastName')
});

let president = President.create({
  firstName: 'Barack',
  lastName: 'Obama'
});

president.get('fullName'); // 'Barack Obama'