c# - 空 setter 与属性中没有 setter

Question

这两个属性实现有什么区别？

public override string A
{
    get { return "s"; }
    set { }
}

public override string A
{
    get { return "s"; }
}

Answer 1

好吧，因为 A 是 override，所以基类必须有 both get 和 set (否则代码无法编译)例如

public class MyBase {
  public virtual String A {
    get {
      return "getBaseA";
    }
    set {
      throw new NotSupportedException("setBaseA");
    }
  }
}

现在你有两个不同的派生类:

public class MyDerivedA: MyBase {
  public override String A {
    get {
      return "s";
    }
    set { // set is overridden, now set does nothing
    }
  }
}

public class MyDerivedB: MyBase {
  public override String A {
    get {
      return "s";
    }
    // set is not overridden, same as in the base class
  }
}

让我们调用这两个 set 方法:

// Does nothing: overridden MyDerivedA.A.set is called
MyBase test1 = new MyDerivedA();
test1.A = "Sample";

// Will throw NotSupportedException (base MyBase.A.set is called)
MyBase test2 = new MyDerivedB();
test2.A = "Sample";