Purpose of @ symbol infront of functions [duplicate]

StackOverflow https://stackoverflow.com/questions/17261294

  •  01-06-2022
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Question

I cant understand exactly what @ (this) does infront of class functions. I am using Spine framework, and I got a class Contact which extends Spine.model. I override the Spine methods for creating, deleting, fetching etc, and have them print on the console first like this: 

  create: ->
    console.log('create') 
    super

  destroy: ->
    console.log("destroy")
    super

Some of these methods will work the same if I add @ infront, for example create, while others will not work without @, and others will not work with @. All the methods I override can be seen on the link above.

Is it possible to explain me the effect of @ symbol infront of functions, and why its causing this behaviour?

Was it helpful?

Solution

Answer from mu is too short : You can define class methods by prefixing them with @:

class Box2DUtility
  constructor: () ->
  @drawWorld: (world, context) -> alert 'World drawn!

'

And then draw your world...

Box2DUtility.drawWorld()

Demo: http://jsfiddle.net/ambiguous/5yPh7/

And if you want your drawWorld to act like a constructor then you can say new @ like this:

    class Box2DUtility
      constructor: (s) -> @s = s
      m: () -> alert "instance method called: #{@s}"
      @drawWorld: (s) -> new @ s

Box2DUtility.drawWorld('pancakes').m()

Demo: http://jsfiddle.net/ambiguous/bjPds/1/

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