Example of using updateComponent

UpdatePosition.coffee

Vector = (x,y) ->
  x : x || 0,
  y : y || 0

vAdd = (v,w) -> Vector (v.x + w.x), (v.y + w.y)


clone = (obj) ->
  if not obj? or typeof obj isnt 'object'
    return obj
  newInstance = new obj.constructor()
  for key of obj
    newInstance[key] = clone obj[key]
  return newInstance


updateComponent = (updater, componentName, entity, requirementList) ->
  requirementList = requirementList || [];
  if (requirementList[requirement] for requirement in requirementList)?
    output = clone entity
    output[componentName] = updater output[componentName], output
    return output

updatePosition = (entity) -> 
  updateComponent ((component, entity) -> vAdd component , entity.velocity) , 
  "position" , 
  entity , 
  ["position", "velocity"]