为什么允许设置一个不在C#中设置任何内容的属性?

private set 表示该属性是类外部的只读属性。所以,如果 sp.View = someView; 在类之外使用,则会导致编译器错误。

http://msdn.microsoft.com/en-us/library/bb384054.aspx

使用 Red Gate .NET Reflector

public class ShellPresenter
{
// Fields
[CompilerGenerated]
private IShellView <View>k__BackingField;

// Methods
public ShellPresenter(IShellView view)
{
    this.View = view;
}

// Properties
public IShellView View
{
    [CompilerGenerated]
    get
    {
        return this.<View>k__BackingField;
    }
    [CompilerGenerated]
    private set
    {
        this.<View>k__BackingField = value;
    }
  }
}

   public interface IShellView
    {

    }
    public class View:IShellView
    {
    }

    //public class SomeOtherClass
    //{
    //    static void Main()
    //    {
    //        IShellView someView = new View();
    //        //calling code 
    //        ShellPresenter sp = new ShellPresenter();

    //        //Why is this allowed? 
    //        sp.View = someView;//setting a private set outside the ShellPresenter class is NOT allowed.
    //    }
    //}

    public class ShellPresenter
    {
        public ShellPresenter()
        {
        }
        public ShellPresenter(IShellView view)
        {
            View = view;

        }
        static void Main()
        {
            IShellView someView = new View();
            //calling code 
            ShellPresenter sp = new ShellPresenter();

            //Why is this allowed? 
            sp.View = someView;//because now its within the class
        }
        public IShellView View { get; private set; }
    } 

C编译器为您生成后端字段。这种语法是为支持匿名类型而引入的(比如 new { A = 1, B = "foo" } )