嵌套接口的替代方法(在C#中不可能)

Question

我在这种情况下使用接口主要是作为对象的不可变实例的句柄.问题是不允许在C#中嵌套接口.这是代码:

public interface ICountry
{
    ICountryInfo Info { get; }

    // Nested interface results in error message:
    // Error    13  'ICountryInfo': interfaces cannot declare types
    public interface ICountryInfo
    {
        int Population { get; }
        string Note { get; }
    }
}


public class Country : ICountry
{
    CountryInfo Info { get; set; }

    public class CountryInfo : ICountry.ICountryInfo
    {
        int Population { get; set; }
        string Note { get; set; }
        .....
    }
    .....
}

我正在寻找替代方案,任何人都有解决方案吗？

Answer 1

VB.NET允许这样做.因此,您只能使用所需的接口定义创建VB.NET程序集:

Public Interface ICountry
  ReadOnly Property Info() As ICountryInfo

  Public Interface ICountryInfo
    ReadOnly Property Population() As Integer
    ReadOnly Property Note() As String
  End Interface
End Interface

至于实现,C#不支持协变返回类型,所以你必须像这样声明你的类:

public class Country : ICountry {
  // this property cannot be declared as CountryInfo
  public ICountry.ICountryInfo Info { get; set; }

  public class CountryInfo : ICountry.ICountryInfo {
    public string Note { get; set; }
    public int Population { get; set; }
  }
}