Prototyping GameObjects with fluent APIs and tagged behaviors in a group

gistfile1.coffee

class GameObject
  constructor: ->
    @x = 0
    @y = 0
    @behaviors = {}

    andObject = @

    @move = (x, y) =>
      @x += x
      @y += y
      andObject

    @move.to = (@x, @y) => @move

    @move.and = @move.to.and = @

    @addBehavior = (behavior) ->

  toString: ->
    JSON.stringify {@x, @y}

g = new GameObject()
g.move(4, 5)
alert g.toString()

g
 .move.to 10, 20
 .and.move 10, 10
alert g.toString()

class BehaviorGroup
  constructor: ->
    @length = 0

    @tags = {}
    @names = {}

  push: (behavior, tags = behavior.tags) ->
    return if Object.hasOwnProperty.call @names, behavior.name

    @[@length] = behavior
    for tag in tags
      @tags[tag] = @tags[tag] or []
      @tags[tag].push @length
    @names[behavior.name] = @length

    ++@length

  pop: -> @[length - 1]

  splice: ->

  forEach: (callback) ->
    for i in [0 .. @length - 1]
      callback @[i]
    null

  byName: (name) -> @[@names[name]]

  byTag: (tag) -> @tags[tag].map (index) => @[index]

bh = new BehaviorGroup()
bh.push
  name: 'abc'
  tags: ['a', 'b', 'c']