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Class to implement publisher

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  1. /*
  2. @author gwilliams
  3. From the article http://justanotherdeveloper.co.uk/2008/07/24/publisher-subscriber-pattern/
  4.  */
  5.  
  6. var Publisher = function(){
  7.  
  8.     var _subscribers = [];
  9.  
  10.     return {
  11.  
  12.         /*
  13.          * Pushes the subscribers callback function into
  14.          * the private _subscribers property.
  15.          */
  16.         subscribe: function(fn){
  17.             _subscribers.push(fn);
  18.         },
  19.  
  20.         /*
  21.          * Method is used to unsubscribe a subscribers callback function
  22.          * from the publisher.
  23.          */
  24.         unsubscribe: function(fn){
  25.  
  26.             _newSubscribers = []; // Create an empty subscriber array
  27.  
  28.             /*
  29.              * Loop through the _subscribers array, checking to see
  30.              * whether the function in 'fn' matches any function in
  31.              * the _subscribers array, if it doesn't match, push it
  32.              * in the _newSubscribers array.
  33.              */
  34.             for (var i = 0; i < _subscribers.length; i++) {
  35.                 if (_subscribers[i] !== fn) {
  36.                     _newSubscribers.push(fn);
  37.                 }
  38.             }
  39.  
  40.             /*
  41.              * Now the _newSubscribers array only contains the callback
  42.              * methods we want we can re-assign it to the private
  43.              * _subscribers property.
  44.              */
  45.             _subscribers = _newSubscribers;
  46.         },
  47.  
  48.         /*
  49.          * Wipes the subscriber list
  50.          */
  51.         wipe: function(){
  52.  
  53.             _subscribers = [];
  54.  
  55.         },
  56.  
  57.         /*
  58.          * Returns all of the current subscribers in an array
  59.          */
  60.         getSubscribers: function(){
  61.             return _subscribers;
  62.         }
  63.  
  64.         /*
  65.          * The notify method is used to invoke all of the callback methods
  66.          * in the _subscribers array, o is the property to be sent to the
  67.          * subscriber method, this can be anything from a string to an object
  68.          * or even JSON.
  69.          */
  70.         notify: function(o){
  71.              for (var i = 0; i < _subscribers.length; i++) {
  72.                 _subscribers[i].call(o);
  73.             }
  74.         }
  75.  
  76.     }
  77.  
  78. };

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