What Do I Use When?

如何选择？

Sometimes new users are confused about when to use computed properties, bindings and observers. Here are some guidelines to help:

刚刚接触Ember.js的用户常常为什么时候使用计算属性、绑定和观察器感到困惑。下面给出几条建议：

Use computed properties to build a new property by synthesizing other properties. Computed properties should not contain application behavior, and should generally not cause any side-effects when called. Except in rare cases, multiple calls to the same computed property should always return the same value (unless the properties it depends on have changed, of course.)
Observers should contain behavior that reacts to changes in another property. Observers are especially useful when you need to perform some behavior after a binding has finished synchronizing.
Bindings are most often used to ensure objects in two different layers are always in sync. For example, you bind your views to your controller using Handlebars.
计算属性通常通过整合其他属性来构建新的属性。计算属性不应该包含任何应用行为，而且不应该在调用的时候产生任何副作用。除了在极少数的情况下，重复调用计算属性应该返回相同的结果（除非其依赖的属性发生了变化）。
观察器应该包含能够针对其他属性的改变做出反应的行为。观察器最适合在一个绑定被同步后需要执行一些操作情况。
绑定常用于确保两个不同层的对象之间的属性是否同步。例如，使用Handlebars绑定视图与控制器。