var Class = {
  create: function() {
    return function() { 
      this.initialize.apply(this, arguments);
    }
  }
}

var Abstract = new Object();

Object.extend = function(destination, source) {
  for (var property in source) {
    destination[property] = source[property];
  }
  return destination;
}

Object.inspect = function(object) {
  try {
    if (object == undefined) return 'undefined';
    if (object == null) return 'null';
    return object.inspect ? object.inspect() : object.toString();
  } catch (e) {
    if (e instanceof RangeError) return '...';
    throw e;
  }
}

Function.prototype.bind = function() {
  var __method = this, args = $A(arguments), object = args.shift();
  return function() {
    return __method.apply(object, args.concat($A(arguments)));
  }
}

Function.prototype.bindAsEventListener = function(object) {
  var __method = this;
  return function(event) {
    return __method.call(object, event || window.event);
  }
}

Object.extend(Number.prototype, {
  toColorPart: function() {
    var digits = this.toString(16);
    if (this < 16) return '0' + digits;
    return digits;
  },

  succ: function() {
    return this + 1;
  },
  
  times: function(iterator) {
    $R(0, this, true).each(iterator);
    return this;
  }
});

var Try = {
  these: function() {
    var returnValue;

    for (var i = 0; i < arguments.length; i++) {
      var lambda = arguments[i];
      try {
        returnValue = lambda();
        break;
      } catch (e) {}
    }

    return returnValue;
  }
}

/*--------------------------------------------------------------------------*/

var PeriodicalExecuter = Class.create();
PeriodicalExecuter.prototype = {
  initialize: function(callback, frequency) {
    this.callback = callback;
    this.frequency = frequency;
    this.currentlyExecuting = false;

    this.registerCallback();
  },

  registerCallback: function() {
    setInterval(this.onTimerEvent.bind(this), this.frequency * 1000);
  },

  onTimerEvent: function() {
    if (!this.currentlyExecuting) {
      try { 
        this.currentlyExecuting = true;
        this.callback(); 
      } finally { 
        this.currentlyExecuting = false;
      }
    }
  }
}