javascript - Coffeescript '@' 或函数和类中的 this

Question

在 coffeescript 中有以下类:

class Canvas
  constructor: (finder) ->
    @canvas = $(finder)
    @mouse_down()
  mouse_down: ->
    @canvas.mousedown (e) ->
      mouse_x = e.pageX - @offsetLeft
      ### ... ###
      @redraw()
  redraw: ->
    ### ... ###

问题是在mousedown函数中调用类对象redraw方法。最好的解决方案是什么？我只发现:

  mouse_down: ->
    @canvas.mousedown (e) =>
      mouse_x = e.pageX - @canvas[0].offsetLeft
      ### ... ###
      @redraw()

Answer 1

检查一下:

class Canvas
   constructor: (finder) ->
      @canvas = $(finder)
      @mouse_down()
   mouse_down: ->
      redrawCallback = @redraw
      @canvas.mousedown (e) ->
         mouse_x = e.pageX - @offsetLeft
         ### ... ###
         redrawCallback()
   redraw: ->
      ### ... ###

如果重绘以任何方式引用@(Canvas 类)，那么这样做会更好(无论如何它更安全):

class Canvas
  constructor: (finder) ->
     @canvas = $(finder)
     @mouse_down()
  mouse_down: ->
     redrawCallback = => @redraw()
     @canvas.mousedown (e) ->
        mouse_x = e.pageX - @offsetLeft
        ### ... ###
        redrawCallback()
  redraw: ->
     ### ... ###

附言。虽然这是一个品味问题，但我相信驼峰式大小写比下划线更适合方法名称。