modify a value passed in to the extended Layer class

app.coffee

class Main extends Layer
	constructor: (options={}) ->
		
		# override Layer default
		options.width ?= 200
		
		# introduce the scaling factor
		# Using Nexus 5 @3x by default
		options.finalScale ?= 3
		
		super options
	
	resize: (n) ->
		# returns "undefined"
		print @finalScale
		return n * @finalScale
		
	@define "finalScale",
		get: -> @_finalScale
		set: (value) ->
			@_finalScale = value

	@define "width",
		get: -> @_width
		set: (value) ->
			@_width = @resize(value)


m = new Main
	# this should draw 1000 wide
	width: 500
	# previewing in iPhone so @2x
	finalScale: 2