如何限制受保护的成员只能从第一级子 C# 访问

我有3个级别的课程。

• TopClass
• MiddleClass
• BottomClass

And MiddleClass源自TopClass and BottomClass源自MiddleClass.

我想在以下地区拥有房产TopClass只能从以下位置访问TopClass and MiddleClass不是BottomClass.

正如我正在使用的protected访问修饰符，受保护的属性TopClass可以从以下位置访问BottomClass.

这是我的课程，可以提供更好的见解。

public class TopClass
 {
    private string ThisIsOnlyAccessibleForTopClass { get; set; } 
    protected string ThisIsOnlyAccessibleForTopClassAndMiddleClass { get; set; } // I want this to be accessible only by the MiddleClass 
    public string AccessibleFromEverywhere { get; set; } // this is good as it is public so accessible everywhere

    public virtual void SomeWeirdFunction()
    {
       ThisIsOnlyAccessibleForTopClass = "I can access this here as it is grand father's private member!"; 
    }
 }


 public class MiddleClass : TopClass
 {
     public override void SomeWeirdFunction()
     {
         base.ThisIsOnlyAccessibleForTopClassAndMiddleClass = "As this is a MiddleClass class, I am accessible here.. That is good!";
     }
 }


 public class BottomClass : MiddleClass
 {
     public override void SomeWeirdFunction()
     {
         base.ThisIsOnlyAccessibleForTopClassAndMiddleClass = "I don't want this to be accessible here!";
     }
 }

I want ThisIsOnlyAccessibleForTopClassAndMiddleClass只能从MiddleClass and TopClass，不是来自BottomClass.

我怎样才能做到这一点？因为我无法使用现有的访问修饰符来做到这一点，例如protected, public, internal , private等等..这是否表明我试图在这里打破某种规则？

如果你有一个specific MiddleClass应该具有对成员的特权访问TopClass，你可以把MiddleClass in TopClass作为嵌套类型。嵌套类型可以访问其封闭类型的所有成员。

public class TopClass
{
    private string ThisIsOnlyAccessibleForTopClass { get; set; } 
    private string ThisIsOnlyAccessibleForTopClassAndMiddleClass { get; set; } // I want this to be accessible only by the MiddleClass 
    public string AccessibleFromEverywhere { get; set; } // this is good as it is public so accessible everywhere

    public virtual void SomeWeirdFunction()
    {
        ThisIsOnlyAccessibleForTopClass = "I can access this here as it is grand father's private member!"; 
    }

    public class MiddleClass : TopClass
    {
        public override void SomeWeirdFunction()
        {
            base.ThisIsOnlyAccessibleForTopClassAndMiddleClass = "As this is a MiddleClass class, I am accessible here.. That is good!";
        }
    }

}

public class BottomClass : TopClass.MiddleClass
{
    public override void SomeWeirdFunction()
    {
        // compilation error:
        // base.ThisIsOnlyAccessibleForTopClassAndMiddleClass = "I don't want this to be accessible here!";
    }
}

如果您有一个或多个MiddleClass类在同一个程序集中TopClass，以及所有的BottomClass类将位于另一个程序集中，您可以使用private protected。它的意思是“仅访问既是internal and protected“， 然而protected internal意味着“访问以下类internal or protected".

// in Assembly A

public class TopClass
{
    private string ThisIsOnlyAccessibleForTopClass { get; set; } 
    private protected string ThisIsOnlyAccessibleForTopClassAndMiddleClass { get; set; } // I want this to be accessible only by the MiddleClass 
    public string AccessibleFromEverywhere { get; set; } // this is good as it is public so accessible everywhere

    public virtual void SomeWeirdFunction()
    {
        ThisIsOnlyAccessibleForTopClass = "I can access this here as it is grand father's private member!"; 
    }
}

public class MiddleClass : TopClass
{
    public override void SomeWeirdFunction()
    {
        base.ThisIsOnlyAccessibleForTopClassAndMiddleClass = "As this is a MiddleClass class, I am accessible here.. That is good!";
    }
}

// in Assembly B, which references Assembly A

public class BottomClass : MiddleClass
{
    public override void SomeWeirdFunction()
    {
        // compile error
        // base.ThisIsOnlyAccessibleForTopClassAndMiddleClass = "I don't want this to be accessible here!";
    }
}