Angular中用代理服务实现控制器与指令之间的通信

function instanceMethodCaller(methodName) {    return function caller() {      var handle = this.handle,        args = arguments,        foundInstancesCount = ,        returnValue;      this._instances.forEach(function (instance) {        if ((!handle || handle === instance.$$delegateHandle) && instance.$$filterFn(instance)) {          foundInstancesCount++;          var ret = instance[methodName].apply(instance, args);          if (foundInstancesCount === 1) {            returnValue = ret;          }        }      });      if (!foundInstancesCount && handle) {        return $log.warn('Delegate for handle "' + handle + '" could not find a ' + 'corresponding element with id/delegate="' + handle + '"! ' + methodName + '() was not called!\n' + 'Possible cause: If you are calling ' + methodName + '() immediately, and ' + 'your element with delegate-handle="' + handle + '" is a child of your ' + 'controller, then your element may not be compiled yet. Put a $timeout ' + 'around your call to ' + methodName + '() and try again.');      }      return returnValue;    };  }

function DelegateInstance(instances, handle) {    this._instances = instances;    this.handle = handle;  }

这是一个代理服务，自然会有很多实例，这里用 _instances 这个数组来保存实例。至于 handle 可以理解为实例id。

DelegateService.prototype = DelegateInstance.prototype;

function trueFn() {    return true;  }  DelegateService.prototype._registerInstance = function (instance, handle, filterFn) {    var instances = this._instances;    instance.$$delegateHandle = handle;    instance.$$filterFn = filterFn || trueFn;    instances.push(instance);    return function deregister() {      var index = instances.indexOf(instance);      if (index !== -1) {        instances.splice(index, 1);      }    };  };

DelegateService.prototype.$getByHandle = function (handle) {    return new DelegateInstance(this._instances, handle);  };

angular.module('directive', []).directive('keyboard', ['keyboardService', function (keyboardService) {    return {      replace: true,      templateUrl: 'template/keyboard.html',      link: function (scope, elm, attrs) {        var instance = {          toggle: function (flag) {            window.console.log(flag);          }        };        keyboardService._registerInstance(instance);      }    };  }]).service('keyboardService', angular.DelegateService(['toggle']));

angular.module('app', ['directive']).controller('ctrl', ['$scope', 'keyboardService', function($scope, keyboardService){    keyboardService.toggle(true);    }]);