C＃中的数据绑定概念

问题描述

A级

{

public virtual void WhoAreYou（）{Console.WriteLine（我是A）; }

}

B级：A

{

公共覆盖无效WhoAreYou（）{Console.WriteLine（ 我是B）; }

}

class C：B

{

public new virtual void WhoAreYou（）{Console.WriteLine （我是C）; }

}

D类：C

{

公共覆盖无效WhoAreYou（）{Console.WriteLine（ 我是D）; }

}





C c = new D（）;

c.WhoAreYou（）; //我是D

A a =新D（）;

a.WhoAreYou（）; //我是一个B!!!!

任何人都可以解释一下怎么回事？

class A
{
public virtual void WhoAreYou() { Console.WriteLine("I am an A"); }
}
class B : A
{
public override void WhoAreYou() { Console.WriteLine("I am a B"); }
}
class C : B
{
public new virtual void WhoAreYou() { Console.WriteLine("I am a C"); }
}
class D : C
{
public override void WhoAreYou() { Console.WriteLine("I am a D"); }
}


C c = new D();
c.WhoAreYou();// "I am a D"
A a = new D();
a.WhoAreYou();// "I am a B" !!!!
Can any one explain Whats going On?

推荐答案

"WhoAreYou"-slot 1: A.WhoAreYou —> B.WhoAreYou
"WhoAreYou"-slot 2: C.WhoAreYou —> D.WhoAreYou

他们是无关的，只有相同的名字。发生这种情况是因为在 C 中你没有覆盖slot1-WhoAreYou 并带有覆盖，但重新引入同名的全新方法，同样是虚拟方法。这两个名称针对两个不同的无关插槽 互相隐藏 。如果您的编译时声明是 A 或 B ，则隐含插槽1，如果 C 或 D - 插槽2.



第二种情况，slot1-WhoAreYou 为您提供 A.WhoAreYou 的最新重写版本，该版本由 B定义。 WhoAreYou ，因此我是B。



作为一名有意识的开发人员，您需要了解虚拟方法的工作原理。换句话说，永远记住你是谁。 :-)



这有助于理解OOP级别的内容：

[]，

[]。

-SA

They are unrelated, only have the same name. This happened because in C you did not override "slot1"-WhoAreYou with "override", but reintroduced a totally new method under the same name, again, a virtual one. These two names addressing two different unrelated slots hide each other. If your compile-time declaration is A or B, slot 1 is implied, if C or D — slot 2.

In second case, "slot1"-WhoAreYou gives you the latest overridden version of A.WhoAreYou, which was defined by B.WhoAreYou, hence "I am a B".

You need to learn how virtual methods work very deeply, as a conscious developer. In other words, always remember who are you. :-)

This can help to understand things on the OOP level:
http://en.wikipedia.org/wiki/Dynamic_dispatch[^],
http://en.wikipedia.org/wiki/Virtual_table[^].

—SA

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