Overloading Closure

overloadingFunc.js

http://ejohn.org/apps/learn/#90
function assert(pass, msg){
  var type = pass ? "PASS" : "FAIL";
  jQuery("#results").append("<li class='" + type + "'><b>" + type + "</b> " + msg + "</li>");
}

function addMethod(object, name, fn){
  // Save a reference to the old method
  // that is a closure that has access to older func args
  // This is like a recursive action....
  var old = object[ name ];
  
  //this elegantly create new *closures* every thing calls this function....
  //when calling this helper
  //if not used correctly/abusive
  //is a memory leak.
  
  // Overwrite the method with our new one
  object[ name ] = function(){
    // Check the number of incoming arguments,
    // compared to our overloaded function
    
    function meetAllRules(args){
      return fn.length == args.length;
    }
      
    
    if (meetAllRules(arguments))
      // If there was a match, run the function
      return fn.apply( this, arguments );

    // Otherwise, fallback to the old method
    else if ( typeof old === "function" )
      return old.apply( this, arguments );
    else 
      console.log('cannot resolve....')
  };
}

function Ninjas(){
  var ninjas = [ "Dean Edwards", "Sam Stephenson", "Alex Russell" ];
  addMethod(this, "find", function(){
    return ninjas;
  });
  addMethod(this, "find", function(name){
    var ret = [];
    for ( var i = 0; i < ninjas.length; i++ )
      if ( ninjas[i].indexOf(name) == 0 )
        ret.push( ninjas[i] );
    return ret;
  });
  addMethod(this, "find", function(first, last){
    var ret = [];
    for ( var i = 0; i < ninjas.length; i++ )
      if ( ninjas[i] == (first + " " + last) )
        ret.push( ninjas[i] );
    return ret;
  });
}

var ninjas = new Ninjas();
assert( ninjas.find().length == 3, "Finds all ninjas" );
assert( ninjas.find("Sam").length == 1, "Finds ninjas by first name" );
assert( ninjas.find("Dean", "Edwards").length == 1, "Finds ninjas by first and last name" );
assert( ninjas.find("Alex", "X", "Russell") == null, "Does nothing" );