javascript Decorator pattern.

Decorator.coffee

class Demo

    @filter: (func, args...) ->
        console.log "hello"
        (args...) ->
            console.log this, "before filter", args
            re = func.apply(this, args)
            console.log "after filter", re.hi "ahahahha"
    
    constructor: ->
        @content = "waht"
        # FIXME: using class name is ugly. 
        this.say = Demo.filter this.say
 
    say: (content) ->
        console.log content
        this
        
    hi: (content) ->
        console.log content
        this
        
demo = new Demo

demo.say "hello"