CoffeeScript 类方法和实例方法

类方法和实例方法

问题

你想创建类和实例的方法。

解决方案

类方法

class Songs
  @_titles: 0    # Although it's directly accessible, the leading _ defines it by convention as private property.

  @get_count: ->
    @_titles

  constructor: (@artist, @title) ->
    @constructor._titles++     # Refers to <Classname>._titles, in this case Songs.titles

Songs.get_count()
# => 0

song = new Songs("Rick Astley", "Never Gonna Give You Up")
Songs.get_count()
# => 1

song.get_count()
# => TypeError: Object <Songs> has no method 'get_count'

实例方法

class Songs
  _titles: 0    # Although it's directly accessible, the leading _ defines it by convention as private property.

  get_count: ->
    @_titles

  constructor: (@artist, @title) ->
    @_titles++

song = new Songs("Rick Astley", "Never Gonna Give You Up")
song.get_count()
# => 1

Songs.get_count()
# => TypeError: Object function Songs(artist, title) ... has no method 'get_count'

讨论

Coffeescript会在对象本身中保存类方法(也叫静态方法),而不是在对象原型中(以及单一的对象实例),在保存了记录的同时也将类级的变量保存在中心位置。

以上内容是否对您有帮助:
在线笔记
App下载
App下载

扫描二维码

下载编程狮App

公众号
微信公众号

编程狮公众号

意见反馈
返回顶部