base.js

// goog closure functions

goog = function() {};

goog.inherits = function(childCtor, parentCtor) {
  /** @constructor */
  function tempCtor() {};
  tempCtor.prototype = parentCtor.prototype;
  childCtor.superClass_ = parentCtor.prototype;
  childCtor.prototype = new tempCtor();
  childCtor.prototype.constructor = childCtor;
};

goog.base = function(me, opt_methodName, var_args) {
  var caller = arguments.callee.caller;
  if (caller.superClass_) {
    // This is a constructor. Call the superclass constructor.
    return caller.superClass_.constructor.apply(
        me, Array.prototype.slice.call(arguments, 1));
  }

  var args = Array.prototype.slice.call(arguments, 2);
  var foundCaller = false;
  for (var ctor = me.constructor;
       ctor; ctor = ctor.superClass_ && ctor.superClass_.constructor) {
    if (ctor.prototype[opt_methodName] === caller) {
      foundCaller = true;
    } else if (foundCaller) {
      return ctor.prototype[opt_methodName].apply(me, args);
    }
  }

  // If we did not find the caller in the prototype chain,
  // then one of two things happened:
  // 1) The caller is an instance method.
  // 2) This method was not called by the right caller.
  if (me[opt_methodName] === caller) {
    return me.constructor.prototype[opt_methodName].apply(me, args);
  } else {
    throw Error(
        'goog.base called from a method of one name ' +
        'to a method of a different name');
  }
};