// this is (of course) a horrible simplification
// but assume that all objects have something like this...
function _get_set(prop, value){
  if(typeof(value) !== "undefined"){
    this['_' + prop] = value;
  }
  return this['_' + prop])
}

thing = {
  height: function(value){ _get_set('height', value) }
  width:  function(value){ _get_set('width', value) }
}