使用 CoffeeScript `extends` 与 Backbone.js `extend` 的根本区别 [英] Fundamental differences between utilizing CoffeeScript `extends` vs. Backbone.js `extend`

问题描述

使用 CoffeeScript extends 与 Backbone.js extend 的根本区别是什么?

What are the fundamental differences between utilizing CoffeeScript extends vs. Backbone.js extend?

例如，怎么样

class User extends Backbone.Model

不同于

User = Backbone.Model.extend()

推荐答案

两者是等价的.引用 Backbone.js 变更日志:

The two are intended to be equivalent. To quote the Backbone.js changelog:

0.3.0:Backbone 类现在可以被 CoffeeScript 类无缝继承.

0.3.0: Backbone classes may now be seamlessly inherited by CoffeeScript classes.

CoffeeScript 的 Child extends Parent 和 Backbone 的 Child = Parent.extend() 都做了三个重要的事情:

Both CoffeeScript's Child extends Parent and Backbone's Child = Parent.extend() do three important things:

1. (最重要的) 他们将 Child.prototype 设置为 new ctor，其中 ctor 是一个函数，其原型是 Parent.prototype.这建立了原型继承.
2. 他们将 Parent 的所有静态属性复制到 Child.
3. 他们设置 Child.__super__ = Parent.这主要是为了在Child的方法中支持CoffeeScript的类似Ruby的super关键字.

1. (Most important) They set Child.prototype to new ctor, where ctor is a function whose prototype is Parent.prototype. That establishes prototypal inheritance.
2. They copy all of Parent's static properties onto Child.
3. They set Child.__super__ = Parent. This is mainly to support CoffeeScript's Ruby-like super keyword in Child's methods.

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