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  1. 18 Aug 2011 7:03 AM #1
    jonsykes
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    Default Answered: Anonymous Topic Style Pub/Sub system?

    Answered: Anonymous Topic Style Pub/Sub system?


    Been poking around the code base, but I don't see anything obvious that fills this need.

    Does 4.x not have an anonymous pub/sub system in place?

    Something akin to dojo's publish/subscribe functionality

    http://davidwalsh.name/dojo-pub-sub
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  2. Best Answer Posted by stevil

    It doesn't, but I whipped up a simple mechanism you could extend to your liking:

    Code:
    // Define


Ext.define('PubSub', {
  extend: 'Ext.util.Observable',


  statics: {
    instance: null,


    subscribe: function (topic, listener, scope) {
      // Route messages through instance
      if (!PubSub.instance) {
        PubSub.instance = new this();
      }


      var inst = PubSub.instance;


      // Ensure that event is declared
      if (!inst.events[topic]) {
        inst.addEvents(topic);
      }


      // Then listen on it, with declared scope
      inst.mon(inst, topic, listener, scope || inst);
    },


    publish: function () {
      var inst = PubSub.instance;
      var args = Ext.Array.toArray(arguments);
      var topic = args[0];


      // If the topic has been declared through subscribe
      if (inst && topic && inst.events[topic]) {
        // A quirk in Observable requires me to lowercase the topic name
        // I could have used inst.fireEvent(topic, args.slice(1))
        // but the listener would get the args as a single array 
        // parameter in arguments[0].
        // This allows the published arguments to be passed properly.
       
        var evt = inst.events[topic.toLowerCase()];
        evt.fire.apply(evt, args.slice(1));
      }
    }
  }
});


// Subscribe


PubSub.subscribe('testTopic', function (a, b) {
  alert(a + ' = ' + b);
}, this);


PubSub.subscribe('testTopic', function (a, b) {
  alert(a + ' != ' + b);
}, this);


// Publish


PubSub.publish('testTopic', 'x', 5);
    Note - this is rudimentary - it doesn't have topic management (remove listeners and event declarations), but that could be added.

    hope this helps,

    stevil