Question

我正在尝试解决以下OO问题。我知道它有点味道，但我必须适应现有的设计。请考虑以下代码段：

class Parent
{
   public virtual Context GetContext()
   {
       return new Context(true);
   }

   public virtual GetData()
   {
       var context = GetContext();
       var result = Query(context);
       return result;
   }

   public string GetData2()
   {
       var context = GetContext();
       var result = Query(context);
       return result;
   }

}

class Child : Parent
{
   public override Context GetContext()
   {
       return new Context(false);
   }

   public override GetData()
   {
       var context = GetContext();
       var result = Query(context);
   }
}

我想要以下结果：

new Parent().GetData() => would call Parent.GetContext();
new Parent().GetData2() => would call Parent.GetContext();
new Child().GetData() => would call Child.GetContext();
new Child().GetData2() (not overriden in Child) => would call Parent.GetContext();

实际结果是：

new Parent().GetData() => calls Parent.GetContext();
new Parent().GetData2() => calls Parent.GetContext();
new Child().GetData() => calls Child.GetContext();
new Child().GetData2() => calls Child.GetContext();

Answer 1

你需要覆盖（在这种情况下替换）GetData2函数：

请记住，使用new修饰符不会覆盖基本函数，如果替换它，这意味着如果您将class Child : Parent { public override Context GetContext() { return new Context(false); } public override GetData() { var context = GetContext(); var result = Query(context); } public new string GetData2() { var context = base.GetContext(); return Query(context); } }转换为Child并调用Parent它将调用旧功能，而不是新的功能。

Answer 2

你可以有类似的东西：

class Parent
{
   public virtual Context GetContext()
   {
       return GetContextParentCall();
   }

   private Context GetContextParentCall()
   {
       return new Context(true);
   }

   public virtual GetData()
   {
       var context = GetContext();
       var result = Query(context);
       return result;
   }

   public string GetData2()
   {
       var context = GetContextParentCall();
       var result = Query(context);
       return result;
   }

}

C＃ - 仅在子类中调用重写方法

2 个答案: