小编fer*_*ito的帖子

此代码编译:

def wtf(arg: Any) = {  
  arg match {  
    case Nil => "Nil was passed to arg"  
    case List() => "List() was passed to arg"  
    case _ =>"otherwise"  
  }  
}

但是这个没有:

def wtf(arg: Any) = {  
  arg match {  
    case List() => "List() was passed to arg"  
    case Nil => "Nil was passed to arg"  
    case _ =>"otherwise"  
  }  
}  

行 情况Nil => ...被标记为无法访问的代码.为什么,在第一种情况下,行案例List()=> ...没有标记相同的错误？

天真的困惑:

var arr1 = new Array();
var arr2 = Object.create(Array.prototype);
//Inserting elements in "both arrays"
arr1[0] =0;
arr1[9] =9;
arr2[0] =0;
arr2[9] =9;
arr1.push(10);
arr2.push(10);
console.log(arr1.length); // prints 11
console.log(arr2.length); // prints 1

两个对象都继承了Array.prototype,但它们与[]运算符的行为不同.为什么？