javascript - 在 Coffeescript 中调用方法并传递适当的上下文

Question

这是我拥有的class的简化版本:

class Calculations
  constructor: (amount = 1000) ->
    @amount = amount

  rowOne: =>
    columnOne:   => @amount * 0.1
    columnTwo:   => @amount * 0.2
    columnThree: => @amount * 0.3
    total:       => @_total(context)

  _total: (context) ->
    context.columnOne() + context.columnTwo() + context.columnThree()

我想调用这样的方法:

calc = new Calculations()

calc.rowOne().columnOne()    # And it should return 100
calc.rowOne().columnTwo()    # And it should return 200
calc.rowOne().columnThree()  # And it should return 300
calc.rowOne().total()        # And it should return 600

我怎样才能正确实现这个？当然，当前 _total 方法的实现不起作用，因为我不知道如何在那里传递所需的上下文。这可能吗？

Answer 1

class Calculations
  constructor: (amount = 1000) ->
    @amount = amount

  rowOne: =>
    columnOne:   => @amount * 0.1
    columnTwo:   => @amount * 0.2
    columnThree: => @amount * 0.3
    total:       @_total

  _total: () ->
    this.columnOne() + this.columnTwo() + this.columnThree()