README.md

Trigger

Instead of n number of arguments, use the "envelope" pattern to pass an object instead.

define(function(require)
  var LPE = require("LPE")
  
  LPE.on("card.render", function(data) {
    // use data
    console.log(data.cardId, data.timestamp);
  });
  
  LPE.trigger("card.render", {
    cardId: "2",
    timestamp: new Date()
  });
});

demo-mediator.js

define(function(require) {
  var LPE = require("LPE");
  
  LPE.on("app.start", function(data) {
    // respond app start event
  });
});

demo-observer.js

define(function(require) {
  var Component = require("component");
  
  var component = new Component();
  
  component.on("render", function(data) {
    // respond to render
  });
});

lpevents.js

define(function() {
  var array = [];  
  var push = array.push;
  var slice = array.slice;
  var splice = array.splice;

  var Events = Backbone.Events = {

    // Bind an event to a `callback` function. Passing `"all"` will bind
    // the callback to all events fired.
    on: function(name, callback, context) {
      if (!eventsApi(this, 'on', name, [callback, context]) || !callback) return this;
      this._events || (this._events = {});
      var events = this._events[name] || (this._events[name] = []);
      events.push({callback: callback, context: context, ctx: context || this});
      return this;
    },

    // Bind an event to only be triggered a single time. After the first time
    // the callback is invoked, it will be removed.
    once: function(name, callback, context) {
      if (!eventsApi(this, 'once', name, [callback, context]) || !callback) return this;
      var self = this;
      var once = _.once(function() {
        self.off(name, once);
        callback.apply(this, arguments);
      });
      once._callback = callback;
      return this.on(name, once, context);
    },

    // Remove one or many callbacks. If `context` is null, removes all
    // callbacks with that function. If `callback` is null, removes all
    // callbacks for the event. If `name` is null, removes all bound
    // callbacks for all events.
    off: function(name, callback, context) {
      var retain, ev, events, names, i, l, j, k;
      if (!this._events || !eventsApi(this, 'off', name, [callback, context])) return this;
      if (!name && !callback && !context) {
        this._events = void 0;
        return this;
      }
      names = name ? [name] : _.keys(this._events);
      for (i = 0, l = names.length; i < l; i++) {
        name = names[i];
        if (events = this._events[name]) {
          this._events[name] = retain = [];
          if (callback || context) {
            for (j = 0, k = events.length; j < k; j++) {
              ev = events[j];
              if ((callback && callback !== ev.callback && callback !== ev.callback._callback) ||
                  (context && context !== ev.context)) {
                retain.push(ev);
              }
            }
          }
          if (!retain.length) delete this._events[name];
        }
      }

      return this;
    },

    // Trigger one or many events, firing all bound callbacks. Callbacks are
    // passed the same arguments as `trigger` is, apart from the event name
    // (unless you're listening on `"all"`, which will cause your callback to
    // receive the true name of the event as the first argument).
    trigger: function(name) {
      if (!this._events) return this;
      var args = slice.call(arguments, 1);
      if (!eventsApi(this, 'trigger', name, args)) return this;
      var events = this._events[name];
      var allEvents = this._events.all;
      if (events) triggerEvents(events, args);
      if (allEvents) triggerEvents(allEvents, arguments);
      return this;
    },

    // Tell this object to stop listening to either specific events ... or
    // to every object it's currently listening to.
    stopListening: function(obj, name, callback) {
      var listeningTo = this._listeningTo;
      if (!listeningTo) return this;
      var remove = !name && !callback;
      if (!callback && typeof name === 'object') callback = this;
      if (obj) (listeningTo = {})[obj._listenId] = obj;
      for (var id in listeningTo) {
        obj = listeningTo[id];
        obj.off(name, callback, this);
        if (remove || _.isEmpty(obj._events)) delete this._listeningTo[id];
      }
      return this;
    }

  };

  // Regular expression used to split event strings.
  var eventSplitter = /\s+/;

  // Implement fancy features of the Events API such as multiple event
  // names `"change blur"` and jQuery-style event maps `{change: action}`
  // in terms of the existing API.
  var eventsApi = function(obj, action, name, rest) {
    if (!name) return true;

    // Handle event maps.
    if (typeof name === 'object') {
      for (var key in name) {
        obj[action].apply(obj, [key, name[key]].concat(rest));
      }
      return false;
    }

    // Handle space separated event names.
    if (eventSplitter.test(name)) {
      var names = name.split(eventSplitter);
      for (var i = 0, l = names.length; i < l; i++) {
        obj[action].apply(obj, [names[i]].concat(rest));
      }
      return false;
    }

    return true;
  };

  // A difficult-to-believe, but optimized internal dispatch function for
  // triggering events. Tries to keep the usual cases speedy (most internal
  // Backbone events have 3 arguments).
  var triggerEvents = function(events, args) {
    var ev, i = -1, l = events.length, a1 = args[0], a2 = args[1], a3 = args[2];
    switch (args.length) {
      case 0: while (++i < l) (ev = events[i]).callback.call(ev.ctx); return;
      case 1: while (++i < l) (ev = events[i]).callback.call(ev.ctx, a1); return;
      case 2: while (++i < l) (ev = events[i]).callback.call(ev.ctx, a1, a2); return;
      case 3: while (++i < l) (ev = events[i]).callback.call(ev.ctx, a1, a2, a3); return;
      default: while (++i < l) (ev = events[i]).callback.apply(ev.ctx, args); return;
    }
  };

  var listenMethods = {listenTo: 'on', listenToOnce: 'once'};

  // Inversion-of-control versions of `on` and `once`. Tell *this* object to
  // listen to an event in another object ... keeping track of what it's
  // listening to.
  _.each(listenMethods, function(implementation, method) {
    Events[method] = function(obj, name, callback) {
      var listeningTo = this._listeningTo || (this._listeningTo = {});
      var id = obj._listenId || (obj._listenId = _.uniqueId('l'));
      listeningTo[id] = obj;
      if (!callback && typeof name === 'object') callback = this;
      obj[implementation](name, callback, this);
      return this;
    };
  });

  // Aliases for backwards compatibility.
  Events.bind   = Events.on;
  Events.unbind = Events.off;  
});

mediator.js

define(function(require) {
  var Events = require("lpevents"),
      _ = require("underscore");
  
  function LPE() {}
  
  _.extend(LPE.prototype, {}, Events);
  
  return new LPE();
});

observer.js

define(function(require) {
  var Events = require("lpevents"),
      _ = require("underscore");
  
  function Component() {}
  
  Component.prototype.render = function() {
    this.trigger("render", {
      // use a data "envelope", not "n" arguments
    });
  };
  
  _.extend(Component.prototype, {}, Events);
  
  return Component;
});