"Static" Methods and Properties in CoffeeScript
CoffeeScript provides a natural shorthand notation for creating "static" methods and properties on a class:
class Widget
@count: 0
@addWidget: -> @count++
constructor: ->
Widget.addWidget()
w = new Widget
w2 = new Widget
w3 = new Widget
console.log Widget.count # "3"From the CoffeeScript documentation:
Because in the context of a class definition,
thisis the class object itself (the constructor function), you can assign static properties by using
@property: value, and call functions defined in parent classes:@attr 'title', type: 'text'
Written by Louis Acresti
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5 Responses
Does that actually work? Surely in the method body, @count won't access the class property. Shouldn't it be @constructor.count ?
@micapam: Look closely: notice the @ in front of the name of addWidget? That means the function is actually a static member of the Widget class. More importantly, this in the context of a static method's body actually refers to the class itself!
An interesting note: In the context of an object's member function, @constructor would actually be identical to Widget based on how CoffeeScript implements classes. Try it!
Ahhh that makes sense. Thanks!
@pyros2097 -- nope, that will not work. In the constructor, the value of @addWidget is undefined, because no method called addWidget is specified on the Widget prototype; it is specified on the Widget object itself; a "static" method.
Works fine for me...http://jsfiddle.net/5fsnh76L/
