对象未通过引用传递（CoffeeScript）

Question

I have two classes, one which holds and manages data and one which makes decisions based on the data

module.exports = class Data
    constructor: () ->
         @stuff = 
             foo: 42
             bar: 'something'

and in another file

module.exports = class Mutator
    constructor: (Data) ->
         @foo = Data.foo

and in a main file

Data = require './Data'
Mutator = require './Mutator'

module.exports = class Main
     constructor: () ->
         @data = new Data()
         @mutator = new Mutator(@data)

the problem I'm having is that @data does not seem to be being passed by reference

In main

console.log @Mutator.foo # 42
@data.foo = '24'
console.log @Mutator.foo # still 42

What could be causing this?

Answer 1

@data is being passed by reference but you're throwing that reference way when you pull out the Data.foo value here:

@foo = Data.foo

Your Data is the same as your @data but @foo is just the value of Data.foo . You'd need to hold onto Data rather than Data.foo :

class Mutator
    constructor: (Data) ->
         @data = Data

and then look at @mutator.data.foo . You could probably use defineProperty to define a getter for foo and thus hide the data part and make @mutator.foo work. Have a look at this answer for some notes on how this would work.