Javascript模拟c#方法重载

每次看John Resig的blog，都会有很大的收获！这次和大家一起分享一个Javascript模拟c#方法重载的例子。

  function  loadMethod(object, name, fn){ 
             var  old  =  object[ name ]; 
             if  ( old ) 
                object[ name ]  =   function (){ 
                     if  ( fn.length  ==  arguments.length ) 
                         return  fn.apply(  this , arguments ); 
                     else   if  (  typeof  old  ==  ' function ' ) 
                         return  old.apply(  this , arguments ); 
                }; 
             else  
                object[ name ]  =  fn; 
        }

下面写一个在用户集合中查找特定用户数量的例子

function  UserCount(){ 
            loadMethod( this ,  " find " ,  function (list){ 
                 // 查找所有数量
                 var  i = 0 ;
                 return  list.length;
            }); 
            loadMethod( this ,  " find " ,  function (list,pwd){ 
                 // 查找特定密码的用户数量
                 var  k = 0 ;
                 for ( var  i = 0 ;i < list.length;i ++ )
                {
                     if (list[i].pwd == pwd)
                        k ++ ;
                }
                 return  k;
            }); 
            loadMethod( this ,  " find " ,  function (list,id, pwd){
                 // 查找特定密码和id的用户数量 
                 var  k = 0 ;
                 for ( var  i = 0 ;i < list.length;i ++ )
                {
                     if (list[i].id == id  &&  list[i].pwd == pwd)
                        k ++ ;
                }
                 return  k;
            })
        }

// 定义集合
         var  userlist = new  Array();
        userlist.push({id: " holygrace " ,pwd: " 12345 " });
        userlist.push({id: " JiangYuYang " ,pwd: " 2233 " });
        userlist.push({id: " liyanhong " ,pwd: " 12345 " });
        userlist.push({id: " mayun " ,pwd: " adf " });
        userlist.push({id: " wangzidong " ,pwd: " 3456 " });
        
         var  count = new  UserCount()
        alert( " find(userlist)找到\n " + count.find(userlist) + " 位 " );
        alert( " find(userlist,\ " 12345 \ " )找到\n " + count.find(userlist, " 12345 " ) + " 位 " );
        alert( " find(userlist,\ " holygrace\ " ,\ " 12345 \ " )找到\n " + count.find(userlist, " holygrace " , " 12345 " ) + " 位 " );