AngularJS：包含在同一控制器中

我有一条指令可以包装另一个这样的指令：

<div direction from="origin" to="destination">
    <div direction-map line-color="#e84c3d"></div>
</div>

该direction-map指令已被包含在内，请参见我的代码（Fiddle可在此处）：

var directionController = function() {
    //do stuffs
};
var directionMapController = function() {
    //do other stuffs
};
var Direction = angular.module("direction", [])
    .controller("directionController", directionController)
    .controller("directionMapController", directionMapController)
    .directive("direction", function() {
        var directive = {
            restrict: "AEC",
            controller: "directionController",
            scope: {},
            transclude: true,
            link: {
                pre: function($scope, $element, attrs, controller, transclude) {
                    console.log("direction's controller is directionController : ");
                    console.log(controller.constructor === directionController);//true, that's ok
                    transclude($scope, function(clone) {
                        $element.append(clone);
                    });
                }
            }
        };
        return directive;
    })
    .directive("directionMap", function() {
        var directive = {
            require: "^direction",
            controller: "directionMapController",
            restrict: "AEC",
            scope: true,
            link: {
                pre: function($scope, $element, $attrs, controller) {
                    console.log("directionMap's controller is directionMapController :");
                    console.log(controller.constructor===directionMapController);//false that's not OK!!!!
                }
            }
        };
        return directive;
    });

所以我的问题是：

为什么我的子指令direction-map将其父控制器的参数作为参数（我认为是因为它已被包含），是否有可能避免这种情况，还是我应该重新考虑一下我的代码？