backbone.marionette.js

var Marionette = (function(global, Backbone, _){
  "use strict";

  // Define and export the Marionette namespace
  var Marionette = {};
  Backbone.Marionette = Marionette;

  // Get the DOM manipulator for later use
  Marionette.$ = Backbone.$;

// Helpers
// -------

// For slicing `arguments` in functions
var protoSlice = Array.prototype.slice;
function slice(args) {
  return protoSlice.call(args);
}

function throwError(message, name) {
  var error = new Error(message);
  error.name = name || 'Error';
  throw error;
}

// Marionette.extend
// -----------------

// Borrow the Backbone `extend` method so we can use it as needed
Marionette.extend = Backbone.Model.extend;

// Marionette.getOption
// --------------------

// Retrieve an object, function or other value from a target
// object or its `options`, with `options` taking precedence.
Marionette.getOption = function(target, optionName){
  if (!target || !optionName){ return; }
  var value;

  if (target.options && (optionName in target.options) && (target.options[optionName] !== undefined)){
    value = target.options[optionName];
  } else {
    value = target[optionName];
  }

  return value;
};

// Marionette.normalizeMethods
// ----------------------

// Pass in a mapping of events => functions or function names
// and return a mapping of events => functions
Marionette.normalizeMethods = function(hash) {
  var normalizedHash = {}, method;
  _.each(hash, function(fn, name) {
    method = fn;
    if (!_.isFunction(method)) {
      method = this[method];
    }
    if (!method) {
      return;
    }
    normalizedHash[name] = method;
  }, this);
  return normalizedHash;
};
// Trigger an event and/or a corresponding method name. Examples:
//
// `this.triggerMethod("foo")` will trigger the "foo" event and
// call the "onFoo" method.
//
// `this.triggerMethod("foo:bar")` will trigger the "foo:bar" event and
// call the "onFooBar" method.
Marionette.triggerMethod = (function(){

  // split the event name on the ":"
  var splitter = /(^|:)(\w)/gi;

  // take the event section ("section1:section2:section3")
  // and turn it in to uppercase name
  function getEventName(match, prefix, eventName) {
    return eventName.toUpperCase();
  }

  // actual triggerMethod implementation
  var triggerMethod = function(event) {
    // get the method name from the event name
    var methodName = 'on' + event.replace(splitter, getEventName);
    var method = this[methodName];

    // trigger the event, if a trigger method exists
    if(_.isFunction(this.trigger)) {
      this.trigger.apply(this, arguments);
    }

    // call the onMethodName if it exists
    if (_.isFunction(method)) {
      // pass all arguments, except the event name
      return method.apply(this, _.tail(arguments));
    }
  };

  return triggerMethod;
})();

// DOMRefresh
// ----------
//
// Monitor a view's state, and after it has been rendered and shown
// in the DOM, trigger a "dom:refresh" event every time it is
// re-rendered.

Marionette.MonitorDOMRefresh = (function(documentElement){
  // track when the view has been shown in the DOM,
  // using a Marionette.Region (or by other means of triggering "show")
  function handleShow(view){
    view._isShown = true;
    triggerDOMRefresh(view);
  }

  // track when the view has been rendered
  function handleRender(view){
    view._isRendered = true;
    triggerDOMRefresh(view);
  }

  // Trigger the "dom:refresh" event and corresponding "onDomRefresh" method
  function triggerDOMRefresh(view){
    if (view._isShown && view._isRendered && isInDOM(view)){
      if (_.isFunction(view.triggerMethod)){
        view.triggerMethod("dom:refresh");
      }
    }
  }

  function isInDOM(view) {
    return documentElement.contains(view.el);
  }

  // Export public API
  return function(view){
    view.listenTo(view, "show", function(){
      handleShow(view);
    });

    view.listenTo(view, "render", function(){
      handleRender(view);
    });
  };
})(document.documentElement);


// Marionette.bindEntityEvents & unbindEntityEvents
// ---------------------------
//
// These methods are used to bind/unbind a backbone "entity" (collection/model)
// to methods on a target object.
//
// The first parameter, `target`, must have a `listenTo` method from the
// EventBinder object.
//
// The second parameter is the entity (Backbone.Model or Backbone.Collection)
// to bind the events from.
//
// The third parameter is a hash of { "event:name": "eventHandler" }
// configuration. Multiple handlers can be separated by a space. A
// function can be supplied instead of a string handler name.

(function(Marionette){
  "use strict";

  // Bind the event to handlers specified as a string of
  // handler names on the target object
  function bindFromStrings(target, entity, evt, methods){
    var methodNames = methods.split(/\s+/);

    _.each(methodNames,function(methodName) {

      var method = target[methodName];
      if(!method) {
        throwError("Method '"+ methodName +"' was configured as an event handler, but does not exist.");
      }

      target.listenTo(entity, evt, method, target);
    });
  }

  // Bind the event to a supplied callback function
  function bindToFunction(target, entity, evt, method){
      target.listenTo(entity, evt, method, target);
  }

  // Bind the event to handlers specified as a string of
  // handler names on the target object
  function unbindFromStrings(target, entity, evt, methods){
    var methodNames = methods.split(/\s+/);

    _.each(methodNames,function(methodName) {
      var method = target[methodName];
      target.stopListening(entity, evt, method, target);
    });
  }

  // Bind the event to a supplied callback function
  function unbindToFunction(target, entity, evt, method){
      target.stopListening(entity, evt, method, target);
  }


  // generic looping function
  function iterateEvents(target, entity, bindings, functionCallback, stringCallback){
    if (!entity || !bindings) { return; }

    // allow the bindings to be a function
    if (_.isFunction(bindings)){
      bindings = bindings.call(target);
    }

    // iterate the bindings and bind them
    _.each(bindings, function(methods, evt){

      // allow for a function as the handler,
      // or a list of event names as a string
      if (_.isFunction(methods)){
        functionCallback(target, entity, evt, methods);
      } else {
        stringCallback(target, entity, evt, methods);
      }

    });
  }

  // Export Public API
  Marionette.bindEntityEvents = function(target, entity, bindings){
    iterateEvents(target, entity, bindings, bindToFunction, bindFromStrings);
  };

  Marionette.unbindEntityEvents = function(target, entity, bindings){
    iterateEvents(target, entity, bindings, unbindToFunction, unbindFromStrings);
  };

})(Marionette);


// Callbacks
// ---------

// A simple way of managing a collection of callbacks
// and executing them at a later point in time, using jQuery's
// `Deferred` object.
Marionette.Callbacks = function(){
  this._deferred = Marionette.$.Deferred();
  this._callbacks = [];
};

_.extend(Marionette.Callbacks.prototype, {

  // Add a callback to be executed. Callbacks added here are
  // guaranteed to execute, even if they are added after the
  // `run` method is called.
  add: function(callback, contextOverride){
    this._callbacks.push({cb: callback, ctx: contextOverride});

    this._deferred.done(function(context, options){
      if (contextOverride){ context = contextOverride; }
      callback.call(context, options);
    });
  },

  // Run all registered callbacks with the context specified.
  // Additional callbacks can be added after this has been run
  // and they will still be executed.
  run: function(options, context){
    this._deferred.resolve(context, options);
  },

  // Resets the list of callbacks to be run, allowing the same list
  // to be run multiple times - whenever the `run` method is called.
  reset: function(){
    var callbacks = this._callbacks;
    this._deferred = Marionette.$.Deferred();
    this._callbacks = [];

    _.each(callbacks, function(cb){
      this.add(cb.cb, cb.ctx);
    }, this);
  }
});


// Marionette Controller
// ---------------------
//
// A multi-purpose object to use as a controller for
// modules and routers, and as a mediator for workflow
// and coordination of other objects, views, and more.
Marionette.Controller = function(options){
  this.triggerMethod = Marionette.triggerMethod;
  this.options = options || {};

  if (_.isFunction(this.initialize)){
    this.initialize(this.options);
  }
};

Marionette.Controller.extend = Marionette.extend;

// Controller Methods
// --------------

// Ensure it can trigger events with Backbone.Events
_.extend(Marionette.Controller.prototype, Backbone.Events, {
  close: function(){
    this.stopListening();
    this.triggerMethod("close");
    this.unbind();
  }
});

// Region
// ------
//
// Manage the visual regions of your composite application. See
// http://lostechies.com/derickbailey/2011/12/12/composite-js-apps-regions-and-region-managers/

Marionette.Region = function(options){
  this.options = options || {};
  this.el = Marionette.getOption(this, "el");

  if (!this.el){
    var err = new Error("An 'el' must be specified for a region.");
    err.name = "NoElError";
    throw err;
  }

  if (this.initialize){
    var args = Array.prototype.slice.apply(arguments);
    this.initialize.apply(this, args);
  }
};


// Region Type methods
// -------------------

_.extend(Marionette.Region, {

  // Build an instance of a region by passing in a configuration object
  // and a default region type to use if none is specified in the config.
  //
  // The config object should either be a string as a jQuery DOM selector,
  // a Region type directly, or an object literal that specifies both
  // a selector and regionType:
  //
  // ```js
  // {
  //   selector: "#foo",
  //   regionType: MyCustomRegion
  // }
  // ```
  //
  buildRegion: function(regionConfig, defaultRegionType){
    var regionIsString = (typeof regionConfig === "string");
    var regionSelectorIsString = (typeof regionConfig.selector === "string");
    var regionTypeIsUndefined = (typeof regionConfig.regionType === "undefined");
    var regionIsType = (typeof regionConfig === "function");

    if (!regionIsType && !regionIsString && !regionSelectorIsString) {
      throw new Error("Region must be specified as a Region type, a selector string or an object with selector property");
    }

    var selector, RegionType;

    // get the selector for the region

    if (regionIsString) {
      selector = regionConfig;
    }

    if (regionConfig.selector) {
      selector = regionConfig.selector;
      delete regionConfig.selector;
    }

    // get the type for the region

    if (regionIsType){
      RegionType = regionConfig;
    }

    if (!regionIsType && regionTypeIsUndefined) {
      RegionType = defaultRegionType;
    }

    if (regionConfig.regionType) {
      RegionType = regionConfig.regionType;
      delete regionConfig.regionType;
    }

    if (regionIsString || regionIsType) {
      regionConfig = {};
    }

    regionConfig.el = selector;

    // build the region instance
    var region = new RegionType(regionConfig);

    // override the `getEl` function if we have a parentEl
    // this must be overridden to ensure the selector is found
    // on the first use of the region. if we try to assign the
    // region's `el` to `parentEl.find(selector)` in the object
    // literal to build the region, the element will not be
    // guaranteed to be in the DOM already, and will cause problems
    if (regionConfig.parentEl){
      region.getEl = function(selector) {
        var parentEl = regionConfig.parentEl;
        if (_.isFunction(parentEl)){
          parentEl = parentEl();
        }
        return parentEl.find(selector);
      };
    }

    return region;
  }

});

// Region Instance Methods
// -----------------------

_.extend(Marionette.Region.prototype, Backbone.Events, {

  // Displays a backbone view instance inside of the region.
  // Handles calling the `render` method for you. Reads content
  // directly from the `el` attribute. Also calls an optional
  // `onShow` and `close` method on your view, just after showing
  // or just before closing the view, respectively.
  show: function(view){
    this.ensureEl();

    var isViewClosed = view.isClosed || _.isUndefined(view.$el);
    var isDifferentView = view !== this.currentView;

    if (isDifferentView) {
      this.close();
    }

    view.render();

    if (isDifferentView || isViewClosed) {
      this.open(view);
    }

    this.currentView = view;

    Marionette.triggerMethod.call(this, "show", view);
    Marionette.triggerMethod.call(view, "show");
  },

  ensureEl: function(){
    if (!this.$el || this.$el.length === 0){
      this.$el = this.getEl(this.el);
    }
  },

  // Override this method to change how the region finds the
  // DOM element that it manages. Return a jQuery selector object.
  getEl: function(selector){
    return Marionette.$(selector);
  },

  // Override this method to change how the new view is
  // appended to the `$el` that the region is managing
  open: function(view){
    this.$el.empty().append(view.el);
  },

  // Close the current view, if there is one. If there is no
  // current view, it does nothing and returns immediately.
  close: function(){
    var view = this.currentView;
    if (!view || view.isClosed){ return; }

    // call 'close' or 'remove', depending on which is found
    if (view.close) { view.close(); }
    else if (view.remove) { view.remove(); }

    Marionette.triggerMethod.call(this, "close", view);

    delete this.currentView;
  },

  // Attach an existing view to the region. This
  // will not call `render` or `onShow` for the new view,
  // and will not replace the current HTML for the `el`
  // of the region.
  attachView: function(view){
    this.currentView = view;
  },

  // Reset the region by closing any existing view and
  // clearing out the cached `$el`. The next time a view
  // is shown via this region, the region will re-query the
  // DOM for the region's `el`.
  reset: function(){
    this.close();
    delete this.$el;
  }
});

// Copy the `extend` function used by Backbone's classes
Marionette.Region.extend = Marionette.extend;

// Marionette.RegionManager
// ------------------------
//
// Manage one or more related `Marionette.Region` objects.
Marionette.RegionManager = (function(Marionette){

  var RegionManager = Marionette.Controller.extend({
    constructor: function(options){
      this._regions = {};
      Marionette.Controller.prototype.constructor.call(this, options);
    },

    // Add multiple regions using an object literal, where
    // each key becomes the region name, and each value is
    // the region definition.
    addRegions: function(regionDefinitions, defaults){
      var regions = {};

      _.each(regionDefinitions, function(definition, name){
        if (typeof definition === "string"){
          definition = { selector: definition };
        }

        if (definition.selector){
          definition = _.defaults({}, definition, defaults);
        }

        var region = this.addRegion(name, definition);
        regions[name] = region;
      }, this);

      return regions;
    },

    // Add an individual region to the region manager,
    // and return the region instance
    addRegion: function(name, definition){
      var region;

      var isObject = _.isObject(definition);
      var isString = _.isString(definition);
      var hasSelector = !!definition.selector;

      if (isString || (isObject && hasSelector)){
        region = Marionette.Region.buildRegion(definition, Marionette.Region);
      } else if (_.isFunction(definition)){
        region = Marionette.Region.buildRegion(definition, Marionette.Region);
      } else {
        region = definition;
      }

      this._store(name, region);
      this.triggerMethod("region:add", name, region);
      return region;
    },

    // Get a region by name
    get: function(name){
      return this._regions[name];
    },

    // Remove a region by name
    removeRegion: function(name){
      var region = this._regions[name];
      this._remove(name, region);
    },

    // Close all regions in the region manager, and
    // remove them
    removeRegions: function(){
      _.each(this._regions, function(region, name){
        this._remove(name, region);
      }, this);
    },

    // Close all regions in the region manager, but
    // leave them attached
    closeRegions: function(){
      _.each(this._regions, function(region, name){
        region.close();
      }, this);
    },

    // Close all regions and shut down the region
    // manager entirely
    close: function(){
      this.removeRegions();
      var args = Array.prototype.slice.call(arguments);
      Marionette.Controller.prototype.close.apply(this, args);
    },

    // internal method to store regions
    _store: function(name, region){
      this._regions[name] = region;
      this._setLength();
    },

    // internal method to remove a region
    _remove: function(name, region){
      region.close();
      delete this._regions[name];
      this._setLength();
      this.triggerMethod("region:remove", name, region);
    },

    // set the number of regions current held
    _setLength: function(){
      this.length = _.size(this._regions);
    }

  });

  // Borrowing this code from Backbone.Collection:
  // http://backbonejs.org/docs/backbone.html#section-106
  //
  // Mix in methods from Underscore, for iteration, and other
  // collection related features.
  var methods = ['forEach', 'each', 'map', 'find', 'detect', 'filter',
    'select', 'reject', 'every', 'all', 'some', 'any', 'include',
    'contains', 'invoke', 'toArray', 'first', 'initial', 'rest',
    'last', 'without', 'isEmpty', 'pluck'];

  _.each(methods, function(method) {
    RegionManager.prototype[method] = function() {
      var regions = _.values(this._regions);
      var args = [regions].concat(_.toArray(arguments));
      return _[method].apply(_, args);
    };
  });

  return RegionManager;
})(Marionette);


// Template Cache
// --------------

// Manage templates stored in `<script>` blocks,
// caching them for faster access.
Marionette.TemplateCache = function(templateId){
  this.templateId = templateId;
};

// TemplateCache object-level methods. Manage the template
// caches from these method calls instead of creating
// your own TemplateCache instances
_.extend(Marionette.TemplateCache, {
  templateCaches: {},

  // Get the specified template by id. Either
  // retrieves the cached version, or loads it
  // from the DOM.
  get: function(templateId){
    var cachedTemplate = this.templateCaches[templateId];

    if (!cachedTemplate){
      cachedTemplate = new Marionette.TemplateCache(templateId);
      this.templateCaches[templateId] = cachedTemplate;
    }

    return cachedTemplate.load();
  },

  // Clear templates from the cache. If no arguments
  // are specified, clears all templates:
  // `clear()`
  //
  // If arguments are specified, clears each of the
  // specified templates from the cache:
  // `clear("#t1", "#t2", "...")`
  clear: function(){
    var i;
    var args = slice(arguments);
    var length = args.length;

    if (length > 0){
      for(i=0; i<length; i++){
        delete this.templateCaches[args[i]];
      }
    } else {
      this.templateCaches = {};
    }
  }
});

// TemplateCache instance methods, allowing each
// template cache object to manage its own state
// and know whether or not it has been loaded
_.extend(Marionette.TemplateCache.prototype, {

  // Internal method to load the template
  load: function(){
    // Guard clause to prevent loading this template more than once
    if (this.compiledTemplate){
      return this.compiledTemplate;
    }

    // Load the template and compile it
    var template = this.loadTemplate(this.templateId);
    this.compiledTemplate = this.compileTemplate(template);

    return this.compiledTemplate;
  },

  // Load a template from the DOM, by default. Override
  // this method to provide your own template retrieval
  // For asynchronous loading with AMD/RequireJS, consider
  // using a template-loader plugin as described here:
  // https://github.com/marionettejs/backbone.marionette/wiki/Using-marionette-with-requirejs
  loadTemplate: function(templateId){
    var template = Marionette.$(templateId).html();

    if (!template || template.length === 0){
      throwError("Could not find template: '" + templateId + "'", "NoTemplateError");
    }

    return template;
  },

  // Pre-compile the template before caching it. Override
  // this method if you do not need to pre-compile a template
  // (JST / RequireJS for example) or if you want to change
  // the template engine used (Handebars, etc).
  compileTemplate: function(rawTemplate){
    return _.template(rawTemplate);
  }
});


// Renderer
// --------

// Render a template with data by passing in the template
// selector and the data to render.
Marionette.Renderer = {

  // Render a template with data. The `template` parameter is
  // passed to the `TemplateCache` object to retrieve the
  // template function. Override this method to provide your own
  // custom rendering and template handling for all of Marionette.
  render: function(template, data){

    if (!template) {
      var error = new Error("Cannot render the template since it's false, null or undefined.");
      error.name = "TemplateNotFoundError";
      throw error;
    }

    var templateFunc;
    if (typeof template === "function"){
      templateFunc = template;
    } else {
      templateFunc = Marionette.TemplateCache.get(template);
    }

    return templateFunc(data);
  }
};



// Marionette.View
// ---------------

// The core view type that other Marionette views extend from.
Marionette.View = Backbone.View.extend({

  constructor: function(options){
    _.bindAll(this, "render");

    var args = Array.prototype.slice.apply(arguments);

    // this exposes view options to the view initializer
    // this is a backfill since backbone removed the assignment
    // of this.options
    // at some point however this may be removed
    this.options = _.extend({}, _.result(this, 'options'), _.isFunction(options) ? options.call(this) : options);

    // parses out the @ui DSL for events
    this.events = this.normalizeUIKeys(_.result(this, 'events'));
    Backbone.View.prototype.constructor.apply(this, args);

    Marionette.MonitorDOMRefresh(this);
    this.listenTo(this, "show", this.onShowCalled, this);
  },

  // import the "triggerMethod" to trigger events with corresponding
  // methods if the method exists
  triggerMethod: Marionette.triggerMethod,

  // Imports the "normalizeMethods" to transform hashes of
  // events=>function references/names to a hash of events=>function references
  normalizeMethods: Marionette.normalizeMethods,

  // Get the template for this view
  // instance. You can set a `template` attribute in the view
  // definition or pass a `template: "whatever"` parameter in
  // to the constructor options.
  getTemplate: function(){
    return Marionette.getOption(this, "template");
  },

  // Mix in template helper methods. Looks for a
  // `templateHelpers` attribute, which can either be an
  // object literal, or a function that returns an object
  // literal. All methods and attributes from this object
  // are copies to the object passed in.
  mixinTemplateHelpers: function(target){
    target = target || {};
    var templateHelpers = Marionette.getOption(this, "templateHelpers");
    if (_.isFunction(templateHelpers)){
      templateHelpers = templateHelpers.call(this);
    }
    return _.extend(target, templateHelpers);
  },

  // allows for the use of the @ui. syntax within
  // a given key for triggers and events
  // swaps the @ui with the associated selector
  normalizeUIKeys: function(hash) {
    if (typeof(hash) === "undefined") {
      return;
    }

    _.each(_.keys(hash), function(v) {
      var split = v.split("@ui.");
      if (split.length === 2) {
        hash[split[0]+this.ui[split[1]]] = hash[v];
        delete hash[v];
      }
    }, this);

    return hash;
  },

  // Configure `triggers` to forward DOM events to view
  // events. `triggers: {"click .foo": "do:foo"}`
  configureTriggers: function(){
    if (!this.triggers) { return; }

    var triggerEvents = {};

    // Allow `triggers` to be configured as a function
    var triggers = this.normalizeUIKeys(_.result(this, "triggers"));

    // Configure the triggers, prevent default
    // action and stop propagation of DOM events
    _.each(triggers, function(value, key){

      var hasOptions = _.isObject(value);
      var eventName = hasOptions ? value.event : value;

      // build the event handler function for the DOM event
      triggerEvents[key] = function(e){

        // stop the event in its tracks
        if (e) {
          var prevent = e.preventDefault;
          var stop = e.stopPropagation;

          var shouldPrevent = hasOptions ? value.preventDefault : prevent;
          var shouldStop = hasOptions ? value.stopPropagation : stop;

          if (shouldPrevent && prevent) { prevent.apply(e); }
          if (shouldStop && stop) { stop.apply(e); }
        }

        // build the args for the event
        var args = {
          view: this,
          model: this.model,
          collection: this.collection
        };

        // trigger the event
        this.triggerMethod(eventName, args);
      };

    }, this);

    return triggerEvents;
  },

  // Overriding Backbone.View's delegateEvents to handle
  // the `triggers`, `modelEvents`, and `collectionEvents` configuration
  delegateEvents: function(events){
    this._delegateDOMEvents(events);
    Marionette.bindEntityEvents(this, this.model, Marionette.getOption(this, "modelEvents"));
    Marionette.bindEntityEvents(this, this.collection, Marionette.getOption(this, "collectionEvents"));
  },

  // internal method to delegate DOM events and triggers
  _delegateDOMEvents: function(events){
    events = events || this.events;
    if (_.isFunction(events)){ events = events.call(this); }

    var combinedEvents = {};
    var triggers = this.configureTriggers();
    _.extend(combinedEvents, events, triggers);

    Backbone.View.prototype.delegateEvents.call(this, combinedEvents);
  },

  // Overriding Backbone.View's undelegateEvents to handle unbinding
  // the `triggers`, `modelEvents`, and `collectionEvents` config
  undelegateEvents: function(){
    var args = Array.prototype.slice.call(arguments);
    Backbone.View.prototype.undelegateEvents.apply(this, args);

    Marionette.unbindEntityEvents(this, this.model, Marionette.getOption(this, "modelEvents"));
    Marionette.unbindEntityEvents(this, this.collection, Marionette.getOption(this, "collectionEvents"));
  },

  // Internal method, handles the `show` event.
  onShowCalled: function(){},

  // Default `close` implementation, for removing a view from the
  // DOM and unbinding it. Regions will call this method
  // for you. You can specify an `onClose` method in your view to
  // add custom code that is called after the view is closed.
  close: function(){
    if (this.isClosed) { return; }

    // allow the close to be stopped by returning `false`
    // from the `onBeforeClose` method
    var shouldClose = this.triggerMethod("before:close");
    if (shouldClose === false){
      return;
    }

    // mark as closed before doing the actual close, to
    // prevent infinite loops within "close" event handlers
    // that are trying to close other views
    this.isClosed = true;
    this.triggerMethod("close");

    // unbind UI elements
    this.unbindUIElements();

    // remove the view from the DOM
    this.remove();
  },

  // This method binds the elements specified in the "ui" hash inside the view's code with
  // the associated jQuery selectors.
  bindUIElements: function(){
    if (!this.ui) { return; }

    // store the ui hash in _uiBindings so they can be reset later
    // and so re-rendering the view will be able to find the bindings
    if (!this._uiBindings){
      this._uiBindings = this.ui;
    }

    // get the bindings result, as a function or otherwise
    var bindings = _.result(this, "_uiBindings");

    // empty the ui so we don't have anything to start with
    this.ui = {};

    // bind each of the selectors
    _.each(_.keys(bindings), function(key) {
      var selector = bindings[key];
      this.ui[key] = this.$(selector);
    }, this);
  },

  // This method unbinds the elements specified in the "ui" hash
  unbindUIElements: function(){
    if (!this.ui || !this._uiBindings){ return; }

    // delete all of the existing ui bindings
    _.each(this.ui, function($el, name){
      delete this.ui[name];
    }, this);

    // reset the ui element to the original bindings configuration
    this.ui = this._uiBindings;
    delete this._uiBindings;
  }
});

// Item View
// ---------

// A single item view implementation that contains code for rendering
// with underscore.js templates, serializing the view's model or collection,
// and calling several methods on extended views, such as `onRender`.
Marionette.ItemView = Marionette.View.extend({

  // Setting up the inheritance chain which allows changes to
  // Marionette.View.prototype.constructor which allows overriding
  constructor: function(){
    Marionette.View.prototype.constructor.apply(this, slice(arguments));
  },

  // Serialize the model or collection for the view. If a model is
  // found, `.toJSON()` is called. If a collection is found, `.toJSON()`
  // is also called, but is used to populate an `items` array in the
  // resulting data. If both are found, defaults to the model.
  // You can override the `serializeData` method in your own view
  // definition, to provide custom serialization for your view's data.
  serializeData: function(){
    var data = {};

    if (this.model) {
      data = this.model.toJSON();
    }
    else if (this.collection) {
      data = { items: this.collection.toJSON() };
    }

    return data;
  },

  // Render the view, defaulting to underscore.js templates.
  // You can override this in your view definition to provide
  // a very specific rendering for your view. In general, though,
  // you should override the `Marionette.Renderer` object to
  // change how Marionette renders views.
  render: function(){
    this.isClosed = false;

    this.triggerMethod("before:render", this);
    this.triggerMethod("item:before:render", this);

    var data = this.serializeData();
    data = this.mixinTemplateHelpers(data);

    var template = this.getTemplate();
    var html = Marionette.Renderer.render(template, data);

    this.$el.html(html);
    this.bindUIElements();

    this.triggerMethod("render", this);
    this.triggerMethod("item:rendered", this);

    return this;
  },

  // Override the default close event to add a few
  // more events that are triggered.
  close: function(){
    if (this.isClosed){ return; }

    this.triggerMethod('item:before:close');

    Marionette.View.prototype.close.apply(this, slice(arguments));

    this.triggerMethod('item:closed');
  }
});

// Collection View
// ---------------

// A view that iterates over a Backbone.Collection
// and renders an individual ItemView for each model.
Marionette.CollectionView = Marionette.View.extend({
  // used as the prefix for item view events
  // that are forwarded through the collectionview
  itemViewEventPrefix: "itemview",

  // constructor
  constructor: function(options){
    this._initChildViewStorage();

    Marionette.View.prototype.constructor.apply(this, slice(arguments));

    this._initialEvents();
    this.initRenderBuffer();
  },

  // Instead of inserting elements one by one into the page,
  // it's much more performant to insert elements into a document
  // fragment and then insert that document fragment into the page
  initRenderBuffer: function() {
    this.elBuffer = document.createDocumentFragment();
    this._bufferedChildren = [];
  },

  startBuffering: function() {
    this.initRenderBuffer();
    this.isBuffering = true;
  },

  endBuffering: function() {
    this.isBuffering = false;
    this.appendBuffer(this, this.elBuffer);
    this._triggerShowBufferedChildren();
    this.initRenderBuffer();
  },

  _triggerShowBufferedChildren: function () {
    if (this._isShown) {
      _.each(this._bufferedChildren, function (child) {
        Marionette.triggerMethod.call(child, "show");
      });
      this._bufferedChildren = [];
    }
  },

  // Configured the initial events that the collection view
  // binds to.
  _initialEvents: function(){
    if (this.collection){
      this.listenTo(this.collection, "add", this.addChildView, this);
      this.listenTo(this.collection, "remove", this.removeItemView, this);
      this.listenTo(this.collection, "reset", this.render, this);
    }
  },

  // Handle a child item added to the collection
  addChildView: function(item, collection, options){
    this.closeEmptyView();
    var ItemView = this.getItemView(item);
    var index = this.collection.indexOf(item);
    this.addItemView(item, ItemView, index);
  },

  // Override from `Marionette.View` to guarantee the `onShow` method
  // of child views is called.
  onShowCalled: function(){
    this.children.each(function(child){
      Marionette.triggerMethod.call(child, "show");
    });
  },

  // Internal method to trigger the before render callbacks
  // and events
  triggerBeforeRender: function(){
    this.triggerMethod("before:render", this);
    this.triggerMethod("collection:before:render", this);
  },

  // Internal method to trigger the rendered callbacks and
  // events
  triggerRendered: function(){
    this.triggerMethod("render", this);
    this.triggerMethod("collection:rendered", this);
  },

  // Render the collection of items. Override this method to
  // provide your own implementation of a render function for
  // the collection view.
  render: function(){
    this.isClosed = false;
    this.triggerBeforeRender();
    this._renderChildren();
    this.triggerRendered();
    return this;
  },

  // Internal method. Separated so that CompositeView can have
  // more control over events being triggered, around the rendering
  // process
  _renderChildren: function(){
    this.startBuffering();

    this.closeEmptyView();
    this.closeChildren();

    if (!this.isEmpty(this.collection)) {
      this.showCollection();
    } else {
      this.showEmptyView();
    }

    this.endBuffering();
  },

  // Internal method to loop through each item in the
  // collection view and show it
  showCollection: function(){
    var ItemView;
    this.collection.each(function(item, index){
      ItemView = this.getItemView(item);
      this.addItemView(item, ItemView, index);
    }, this);
  },

  // Internal method to show an empty view in place of
  // a collection of item views, when the collection is
  // empty
  showEmptyView: function(){
    var EmptyView = this.getEmptyView();

    if (EmptyView && !this._showingEmptyView){
      this._showingEmptyView = true;
      var model = new Backbone.Model();
      this.addItemView(model, EmptyView, 0);
    }
  },

  // Internal method to close an existing emptyView instance
  // if one exists. Called when a collection view has been
  // rendered empty, and then an item is added to the collection.
  closeEmptyView: function(){
    if (this._showingEmptyView){
      this.closeChildren();
      delete this._showingEmptyView;
    }
  },

  // Retrieve the empty view type
  getEmptyView: function(){
    return Marionette.getOption(this, "emptyView");
  },

  // Retrieve the itemView type, either from `this.options.itemView`
  // or from the `itemView` in the object definition. The "options"
  // takes precedence.
  getItemView: function(item){
    var itemView = Marionette.getOption(this, "itemView");

    if (!itemView){
      throwError("An `itemView` must be specified", "NoItemViewError");
    }

    return itemView;
  },

  // Render the child item's view and add it to the
  // HTML for the collection view.
  addItemView: function(item, ItemView, index){
    // get the itemViewOptions if any were specified
    var itemViewOptions = Marionette.getOption(this, "itemViewOptions");
    if (_.isFunction(itemViewOptions)){
      itemViewOptions = itemViewOptions.call(this, item, index);
    }

    // build the view
    var view = this.buildItemView(item, ItemView, itemViewOptions);

    // set up the child view event forwarding
    this.addChildViewEventForwarding(view);

    // this view is about to be added
    this.triggerMethod("before:item:added", view);

    // Store the child view itself so we can properly
    // remove and/or close it later
    this.children.add(view);

    // Render it and show it
    this.renderItemView(view, index);

    // call the "show" method if the collection view
    // has already been shown
    if (this._isShown && !this.isBuffering){
      Marionette.triggerMethod.call(view, "show");
    }

    // this view was added
    this.triggerMethod("after:item:added", view);

    return view;
  },

  // Set up the child view event forwarding. Uses an "itemview:"
  // prefix in front of all forwarded events.
  addChildViewEventForwarding: function(view){
    var prefix = Marionette.getOption(this, "itemViewEventPrefix");

    // Forward all child item view events through the parent,
    // prepending "itemview:" to the event name
    this.listenTo(view, "all", function(){
      var args = slice(arguments);
      var rootEvent = args[0];
      var itemEvents = this.normalizeMethods(this.getItemEvents());

      args[0] = prefix + ":" + rootEvent;
      args.splice(1, 0, view);

      // call collectionView itemEvent if defined
      if (typeof itemEvents !== "undefined" && _.isFunction(itemEvents[rootEvent])) {
        itemEvents[rootEvent].apply(this, args);
      }

      Marionette.triggerMethod.apply(this, args);
    }, this);
  },

  // returns the value of itemEvents depending on if a function
  getItemEvents: function() {
    if (_.isFunction(this.itemEvents)) {
      return this.itemEvents.call(this);
    }

    return this.itemEvents;
  },

  // render the item view
  renderItemView: function(view, index) {
    view.render();
    this.appendHtml(this, view, index);
  },

  // Build an `itemView` for every model in the collection.
  buildItemView: function(item, ItemViewType, itemViewOptions){
    var options = _.extend({model: item}, itemViewOptions);
    return new ItemViewType(options);
  },

  // get the child view by item it holds, and remove it
  removeItemView: function(item){
    var view = this.children.findByModel(item);
    this.removeChildView(view);
    this.checkEmpty();
  },

  // Remove the child view and close it
  removeChildView: function(view){

    // shut down the child view properly,
    // including events that the collection has from it
    if (view){
      this.stopListening(view);

      // call 'close' or 'remove', depending on which is found
      if (view.close) { view.close(); }
      else if (view.remove) { view.remove(); }

      this.children.remove(view);
    }

    this.triggerMethod("item:removed", view);
  },

  // helper to check if the collection is empty
  isEmpty: function(collection){
    // check if we're empty now
    return !this.collection || this.collection.length === 0;
  },

  // If empty, show the empty view
  checkEmpty: function (){
    if (this.isEmpty(this.collection)){
      this.showEmptyView();
    }
  },

  // You might need to override this if you've overridden appendHtml
  appendBuffer: function(collectionView, buffer) {
    collectionView.$el.append(buffer);
  },

  // Append the HTML to the collection's `el`.
  // Override this method to do something other
  // then `.append`.
  appendHtml: function(collectionView, itemView, index){
    if (collectionView.isBuffering) {
      // buffering happens on reset events and initial renders
      // in order to reduce the number of inserts into the
      // document, which are expensive.
      collectionView.elBuffer.appendChild(itemView.el);
      collectionView._bufferedChildren.push(itemView);
    }
    else {
      // If we've already rendered the main collection, just
      // append the new items directly into the element.
      collectionView.$el.append(itemView.el);
    }
  },

  // Internal method to set up the `children` object for
  // storing all of the child views
  _initChildViewStorage: function(){
    this.children = new Backbone.ChildViewContainer();
  },

  // Handle cleanup and other closing needs for
  // the collection of views.
  close: function(){
    if (this.isClosed){ return; }

    this.triggerMethod("collection:before:close");
    this.closeChildren();
    this.triggerMethod("collection:closed");

    Marionette.View.prototype.close.apply(this, slice(arguments));
  },

  // Close the child views that this collection view
  // is holding on to, if any
  closeChildren: function(){
    this.children.each(function(child){
      this.removeChildView(child);
    }, this);
    this.checkEmpty();
  }
});


// Composite View
// --------------

// Used for rendering a branch-leaf, hierarchical structure.
// Extends directly from CollectionView and also renders an
// an item view as `modelView`, for the top leaf
Marionette.CompositeView = Marionette.CollectionView.extend({

  // Setting up the inheritance chain which allows changes to
  // Marionette.CollectionView.prototype.constructor which allows overriding
  constructor: function(){
    Marionette.CollectionView.prototype.constructor.apply(this, slice(arguments));
  },

  // Configured the initial events that the composite view
  // binds to. Override this method to prevent the initial
  // events, or to add your own initial events.
  _initialEvents: function(){

    // Bind only after composite view in rendered to avoid adding child views
    // to unexisting itemViewContainer
    this.once('render', function () {
      if (this.collection){
        this.listenTo(this.collection, "add", this.addChildView, this);
        this.listenTo(this.collection, "remove", this.removeItemView, this);
        this.listenTo(this.collection, "reset", this._renderChildren, this);
      }
    });

  },

  // Retrieve the `itemView` to be used when rendering each of
  // the items in the collection. The default is to return
  // `this.itemView` or Marionette.CompositeView if no `itemView`
  // has been defined
  getItemView: function(item){
    var itemView = Marionette.getOption(this, "itemView") || this.constructor;

    if (!itemView){
      throwError("An `itemView` must be specified", "NoItemViewError");
    }

    return itemView;
  },

  // Serialize the collection for the view.
  // You can override the `serializeData` method in your own view
  // definition, to provide custom serialization for your view's data.
  serializeData: function(){
    var data = {};

    if (this.model){
      data = this.model.toJSON();
    }

    return data;
  },

  // Renders the model once, and the collection once. Calling
  // this again will tell the model's view to re-render itself
  // but the collection will not re-render.
  render: function(){
    this.isRendered = true;
    this.isClosed = false;
    this.resetItemViewContainer();

    this.triggerBeforeRender();
    var html = this.renderModel();
    this.$el.html(html);
    // the ui bindings is done here and not at the end of render since they
    // will not be available until after the model is rendered, but should be
    // available before the collection is rendered.
    this.bindUIElements();
    this.triggerMethod("composite:model:rendered");

    this._renderChildren();

    this.triggerMethod("composite:rendered");
    this.triggerRendered();
    return this;
  },

  _renderChildren: function(){
    if (this.isRendered){
      this.triggerMethod("composite:collection:before:render");
      Marionette.CollectionView.prototype._renderChildren.call(this);
      this.triggerMethod("composite:collection:rendered");
    }
  },

  // Render an individual model, if we have one, as
  // part of a composite view (branch / leaf). For example:
  // a treeview.
  renderModel: function(){
    var data = {};
    data = this.serializeData();
    data = this.mixinTemplateHelpers(data);

    var template = this.getTemplate();
    return Marionette.Renderer.render(template, data);
  },


  // You might need to override this if you've overridden appendHtml
  appendBuffer: function(compositeView, buffer) {
    var $container = this.getItemViewContainer(compositeView);
    $container.append(buffer);
  },

  // Appends the `el` of itemView instances to the specified
  // `itemViewContainer` (a jQuery selector). Override this method to
  // provide custom logic of how the child item view instances have their
  // HTML appended to the composite view instance.
  appendHtml: function(compositeView, itemView, index){
    if (compositeView.isBuffering) {
      compositeView.elBuffer.appendChild(itemView.el);
      compositeView._bufferedChildren.push(itemView);
    }
    else {
      // If we've already rendered the main collection, just
      // append the new items directly into the element.
      var $container = this.getItemViewContainer(compositeView);
      $container.append(itemView.el);
    }
  },


  // Internal method to ensure an `$itemViewContainer` exists, for the
  // `appendHtml` method to use.
  getItemViewContainer: function(containerView){
    if ("$itemViewContainer" in containerView){
      return containerView.$itemViewContainer;
    }

    var container;
    var itemViewContainer = Marionette.getOption(containerView, "itemViewContainer");
    if (itemViewContainer){

      var selector = _.isFunction(itemViewContainer) ? itemViewContainer.call(this) : itemViewContainer;
      container = containerView.$(selector);
      if (container.length <= 0) {
        throwError("The specified `itemViewContainer` was not found: " + containerView.itemViewContainer, "ItemViewContainerMissingError");
      }

    } else {
      container = containerView.$el;
    }

    containerView.$itemViewContainer = container;
    return container;
  },

  // Internal method to reset the `$itemViewContainer` on render
  resetItemViewContainer: function(){
    if (this.$itemViewContainer){
      delete this.$itemViewContainer;
    }
  }
});


// Layout
// ------

// Used for managing application layouts, nested layouts and
// multiple regions within an application or sub-application.
//
// A specialized view type that renders an area of HTML and then
// attaches `Region` instances to the specified `regions`.
// Used for composite view management and sub-application areas.
Marionette.Layout = Marionette.ItemView.extend({
  regionType: Marionette.Region,

  // Ensure the regions are available when the `initialize` method
  // is called.
  constructor: function (options) {
    options = options || {};

    this._firstRender = true;
    this._initializeRegions(options);

    Marionette.ItemView.prototype.constructor.call(this, options);
  },

  // Layout's render will use the existing region objects the
  // first time it is called. Subsequent calls will close the
  // views that the regions are showing and then reset the `el`
  // for the regions to the newly rendered DOM elements.
  render: function(){

    if (this.isClosed){
      // a previously closed layout means we need to
      // completely re-initialize the regions
      this._initializeRegions();
    }
    if (this._firstRender) {
      // if this is the first render, don't do anything to
      // reset the regions
      this._firstRender = false;
    } else if (!this.isClosed){
      // If this is not the first render call, then we need to
      // re-initializing the `el` for each region
      this._reInitializeRegions();
    }

    var args = Array.prototype.slice.apply(arguments);
    var result = Marionette.ItemView.prototype.render.apply(this, args);

    return result;
  },

  // Handle closing regions, and then close the view itself.
  close: function () {
    if (this.isClosed){ return; }
    this.regionManager.close();
    var args = Array.prototype.slice.apply(arguments);
    Marionette.ItemView.prototype.close.apply(this, args);
  },

  // Add a single region, by name, to the layout
  addRegion: function(name, definition){
    var regions = {};
    regions[name] = definition;
    return this._buildRegions(regions)[name];
  },

  // Add multiple regions as a {name: definition, name2: def2} object literal
  addRegions: function(regions){
    this.regions = _.extend({}, this.regions, regions);
    return this._buildRegions(regions);
  },

  // Remove a single region from the Layout, by name
  removeRegion: function(name){
    delete this.regions[name];
    return this.regionManager.removeRegion(name);
  },

  // internal method to build regions
  _buildRegions: function(regions){
    var that = this;

    var defaults = {
      regionType: Marionette.getOption(this, "regionType"),
      parentEl: function(){ return that.$el; }
    };

    return this.regionManager.addRegions(regions, defaults);
  },

  // Internal method to initialize the regions that have been defined in a
  // `regions` attribute on this layout.
  _initializeRegions: function (options) {
    var regions;
    this._initRegionManager();

    if (_.isFunction(this.regions)) {
      regions = this.regions(options);
    } else {
      regions = this.regions || {};
    }

    this.addRegions(regions);
  },

  // Internal method to re-initialize all of the regions by updating the `el` that
  // they point to
  _reInitializeRegions: function(){
    this.regionManager.closeRegions();
    this.regionManager.each(function(region){
      region.reset();
    });
  },

  // Internal method to initialize the region manager
  // and all regions in it
  _initRegionManager: function(){
    this.regionManager = new Marionette.RegionManager();

    this.listenTo(this.regionManager, "region:add", function(name, region){
      this[name] = region;
      this.trigger("region:add", name, region);
    });

    this.listenTo(this.regionManager, "region:remove", function(name, region){
      delete this[name];
      this.trigger("region:remove", name, region);
    });
  }
});


// AppRouter
// ---------

// Reduce the boilerplate code of handling route events
// and then calling a single method on another object.
// Have your routers configured to call the method on
// your object, directly.
//
// Configure an AppRouter with `appRoutes`.
//
// App routers can only take one `controller` object.
// It is recommended that you divide your controller
// objects in to smaller pieces of related functionality
// and have multiple routers / controllers, instead of
// just one giant router and controller.
//
// You can also add standard routes to an AppRouter.

Marionette.AppRouter = Backbone.Router.extend({

  constructor: function(options){
    Backbone.Router.prototype.constructor.apply(this, slice(arguments));

    this.options = options || {};

    var appRoutes = Marionette.getOption(this, "appRoutes");
    var controller = this._getController();
    this.processAppRoutes(controller, appRoutes);
  },

  // Similar to route method on a Backbone Router but
  // method is called on the controller
  appRoute: function(route, methodName) {
    var controller = this._getController();
    this._addAppRoute(controller, route, methodName);
  },

  // Internal method to process the `appRoutes` for the
  // router, and turn them in to routes that trigger the
  // specified method on the specified `controller`.
  processAppRoutes: function(controller, appRoutes) {
    if (!appRoutes){ return; }

    var routeNames = _.keys(appRoutes).reverse(); // Backbone requires reverted order of routes

    _.each(routeNames, function(route) {
      this._addAppRoute(controller, route, appRoutes[route]);
    }, this);
  },

  _getController: function(){
    return Marionette.getOption(this, "controller");
  },

  _addAppRoute: function(controller, route, methodName){
    var method = controller[methodName];

    if (!method) {
      throw new Error("Method '" + methodName + "' was not found on the controller");
    }

    this.route(route, methodName, _.bind(method, controller));
  }
});


// Application
// -----------

// Contain and manage the composite application as a whole.
// Stores and starts up `Region` objects, includes an
// event aggregator as `app.vent`
Marionette.Application = function(options){
  this._initRegionManager();
  this._initCallbacks = new Marionette.Callbacks();
  this.vent = new Backbone.Wreqr.EventAggregator();
  this.commands = new Backbone.Wreqr.Commands();
  this.reqres = new Backbone.Wreqr.RequestResponse();
  this.submodules = {};

  _.extend(this, options);

  this.triggerMethod = Marionette.triggerMethod;
};

_.extend(Marionette.Application.prototype, Backbone.Events, {
  // Command execution, facilitated by Backbone.Wreqr.Commands
  execute: function(){
    var args = Array.prototype.slice.apply(arguments);
    this.commands.execute.apply(this.commands, args);
  },

  // Request/response, facilitated by Backbone.Wreqr.RequestResponse
  request: function(){
    var args = Array.prototype.slice.apply(arguments);
    return this.reqres.request.apply(this.reqres, args);
  },

  // Add an initializer that is either run at when the `start`
  // method is called, or run immediately if added after `start`
  // has already been called.
  addInitializer: function(initializer){
    this._initCallbacks.add(initializer);
  },

  // kick off all of the application's processes.
  // initializes all of the regions that have been added
  // to the app, and runs all of the initializer functions
  start: function(options){
    this.triggerMethod("initialize:before", options);
    this._initCallbacks.run(options, this);
    this.triggerMethod("initialize:after", options);

    this.triggerMethod("start", options);
  },

  // Add regions to your app.
  // Accepts a hash of named strings or Region objects
  // addRegions({something: "#someRegion"})
  // addRegions({something: Region.extend({el: "#someRegion"}) });
  addRegions: function(regions){
    return this._regionManager.addRegions(regions);
  },

  // Close all regions in the app, without removing them
  closeRegions: function(){
    this._regionManager.closeRegions();
  },

  // Removes a region from your app, by name
  // Accepts the regions name
  // removeRegion('myRegion')
  removeRegion: function(region) {
    this._regionManager.removeRegion(region);
  },

  // Provides alternative access to regions
  // Accepts the region name
  // getRegion('main')
  getRegion: function(region) {
    return this._regionManager.get(region);
  },

  // Create a module, attached to the application
  module: function(moduleNames, moduleDefinition){
    var ModuleClass = Marionette.Module;

    // Overwrite the module class if the user specifies one
    if (moduleDefinition) {
      ModuleClass = moduleDefinition.moduleClass || ModuleClass;
    }

    // slice the args, and add this application object as the
    // first argument of the array
    var args = slice(arguments);
    args.unshift(this);

    // see the Marionette.Module object for more information
    return ModuleClass.create.apply(ModuleClass, args);
  },

  // Internal method to set up the region manager
  _initRegionManager: function(){
    this._regionManager = new Marionette.RegionManager();

    this.listenTo(this._regionManager, "region:add", function(name, region){
      this[name] = region;
    });

    this.listenTo(this._regionManager, "region:remove", function(name, region){
      delete this[name];
    });
  }
});

// Copy the `extend` function used by Backbone's classes
Marionette.Application.extend = Marionette.extend;

// Module
// ------

// A simple module system, used to create privacy and encapsulation in
// Marionette applications
Marionette.Module = function(moduleName, app, options){
  this.moduleName = moduleName;
  this.options = _.extend({}, this.options, options);
  this.initialize = options.initialize || this.initialize;

  // store sub-modules
  this.submodules = {};

  this._setupInitializersAndFinalizers();

  // store the configuration for this module
  this.app = app;
  this.startWithParent = true;

  this.triggerMethod = Marionette.triggerMethod;

  if (_.isFunction(this.initialize)){
    this.initialize(this.options, moduleName, app);
  }
};

Marionette.Module.extend = Marionette.extend;

// Extend the Module prototype with events / listenTo, so that the module
// can be used as an event aggregator or pub/sub.
_.extend(Marionette.Module.prototype, Backbone.Events, {

  // Initialize is an empty function by default. Override it with your own
  // initialization logic when extending Marionette.Module.
  initialize: function(){},

  // Initializer for a specific module. Initializers are run when the
  // module's `start` method is called.
  addInitializer: function(callback){
    this._initializerCallbacks.add(callback);
  },

  // Finalizers are run when a module is stopped. They are used to teardown
  // and finalize any variables, references, events and other code that the
  // module had set up.
  addFinalizer: function(callback){
    this._finalizerCallbacks.add(callback);
  },

  // Start the module, and run all of its initializers
  start: function(options){
    // Prevent re-starting a module that is already started
    if (this._isInitialized){ return; }

    // start the sub-modules (depth-first hierarchy)
    _.each(this.submodules, function(mod){
      // check to see if we should start the sub-module with this parent
      if (mod.startWithParent){
        mod.start(options);
      }
    });

    // run the callbacks to "start" the current module
    this.triggerMethod("before:start", options);

    this._initializerCallbacks.run(options, this);
    this._isInitialized = true;

    this.triggerMethod("start", options);
  },

  // Stop this module by running its finalizers and then stop all of
  // the sub-modules for this module
  stop: function(){
    // if we are not initialized, don't bother finalizing
    if (!this._isInitialized){ return; }
    this._isInitialized = false;

    Marionette.triggerMethod.call(this, "before:stop");

    // stop the sub-modules; depth-first, to make sure the
    // sub-modules are stopped / finalized before parents
    _.each(this.submodules, function(mod){ mod.stop(); });

    // run the finalizers
    this._finalizerCallbacks.run(undefined,this);

    // reset the initializers and finalizers
    this._initializerCallbacks.reset();
    this._finalizerCallbacks.reset();

    Marionette.triggerMethod.call(this, "stop");
  },

  // Configure the module with a definition function and any custom args
  // that are to be passed in to the definition function
  addDefinition: function(moduleDefinition, customArgs){
    this._runModuleDefinition(moduleDefinition, customArgs);
  },

  // Internal method: run the module definition function with the correct
  // arguments
  _runModuleDefinition: function(definition, customArgs){
    if (!definition){ return; }

    // build the correct list of arguments for the module definition
    var args = _.flatten([
      this,
      this.app,
      Backbone,
      Marionette,
      Marionette.$, _,
      customArgs
    ]);

    definition.apply(this, args);
  },

  // Internal method: set up new copies of initializers and finalizers.
  // Calling this method will wipe out all existing initializers and
  // finalizers.
  _setupInitializersAndFinalizers: function(){
    this._initializerCallbacks = new Marionette.Callbacks();
    this._finalizerCallbacks = new Marionette.Callbacks();
  }
});

// Type methods to create modules
_.extend(Marionette.Module, {

  // Create a module, hanging off the app parameter as the parent object.
  create: function(app, moduleNames, moduleDefinition){
    var module = app;

    // get the custom args passed in after the module definition and
    // get rid of the module name and definition function
    var customArgs = slice(arguments);
    customArgs.splice(0, 3);

    // split the module names and get the length
    moduleNames = moduleNames.split(".");
    var length = moduleNames.length;

    // store the module definition for the last module in the chain
    var moduleDefinitions = [];
    moduleDefinitions[length-1] = moduleDefinition;

    // Loop through all the parts of the module definition
    _.each(moduleNames, function(moduleName, i){
      var parentModule = module;
      module = this._getModule(parentModule, moduleName, app, moduleDefinition);
      this._addModuleDefinition(parentModule, module, moduleDefinitions[i], customArgs);
    }, this);

    // Return the last module in the definition chain
    return module;
  },

  _getModule: function(parentModule, moduleName, app, def, args){
    var ModuleClass = Marionette.Module;
    var options = _.extend({}, def);
    if (def) {
      ModuleClass = def.moduleClass || ModuleClass;
    }

    // Get an existing module of this name if we have one
    var module = parentModule[moduleName];

    if (!module){
      // Create a new module if we don't have one
      module = new ModuleClass(moduleName, app, options);
      parentModule[moduleName] = module;
      // store the module on the parent
      parentModule.submodules[moduleName] = module;
    }

    return module;
  },

  _addModuleDefinition: function(parentModule, module, def, args){
    var fn;
    var startWithParent;

    if (_.isFunction(def)){
      // if a function is supplied for the module definition
      fn = def;
      startWithParent = true;

    } else if (_.isObject(def)){
      // if an object is supplied
      fn = def.define;
      startWithParent = (typeof def.startWithParent !== 'undefined') ? def.startWithParent : true;

    } else {
      // if nothing is supplied
      startWithParent = true;
    }

    // add module definition if needed
    if (fn){
      module.addDefinition(fn, args);
    }

    // `and` the two together, ensuring a single `false` will prevent it
    // from starting with the parent
    module.startWithParent = module.startWithParent && startWithParent;

    // setup auto-start if needed
    if (module.startWithParent && !module.startWithParentIsConfigured){

      // only configure this once
      module.startWithParentIsConfigured = true;

      // add the module initializer config
      parentModule.addInitializer(function(options){
        if (module.startWithParent){
          module.start(options);
        }
      });

    }

  }
});



  return Marionette;
})(this, Backbone, _);