如何在C#派生类中永久向下转换泛型设置类？

我拥有多个具备相似行为的服务，这些服务均包含共享设置，同时每个服务还有自身的扩展专属设置，但在派生服务类中无法直接访问这些扩展设置，只能通过强制转换获取。以下是实现示例及问题：

public abstract class BaseSettings<T> where T : ISettings
{
  public string BaseSetting { get; } = "Hello from BaseSettings";
  // other settings, etc.

  public BaseSettings<T>() {}
}

public abstract class BaseService<T> where T : ISettings
{
  public BaseSettings<T> Settings { get; }

  public BaseService(BaseSettings<T> settings)
  {
    Settings = settings;
    Console.WriteLine(Settings.BaseSetting);
  }
}

public class ServiceASettings : BaseSettings<ServiceASettings>, ISettings
{
  public string SettingA { get; } = "Hello from SettingsA";

  public ServiceASettings() {}
}

public class ServiceA : BaseService<ServiceASettings>, IService
{
  public ServiceA(ServiceASettings settings) : base(settings) 
  {
   Console.WriteLine(Settings.SettingA); // 无法访问该属性
   Console.WriteLine((Settings as ServiceASettings).SettingA); // 强制转换后可正常输出
  }
}

// ServiceB, ServiceBSettings; ServiceC, ServiceCSettings; etc...

public class Program
{
  public static void Main(string[] args)
  {
    ServiceASettings settings = new ServiceASettings();
    ServiceA service = new ServiceA(settings);
    // 编译失败，提示ServiceA中没有Settings.SettingA的定义
  }
}

我希望能永久将Settings指定为对应的派生类类型，避免每次都进行强制转换，请问该如何实现？

解决方案 #

修改后的可运行代码如下：

public abstract class BaseSettings
{
  public string BaseSetting { get; } = "Hello from BaseSettings";
  // other settings, etc.

  public BaseSettings() {}
}

public abstract class BaseService<T> where T : ISettings
{
  public T Settings { get; }

  public BaseService(T settings)
  {
    Settings = settings;
    Console.WriteLine(Settings.BaseSetting);
  }
}

public class ServiceASettings : BaseSettings, ISettings
{
  public string SettingA { get; } = "Hello from SettingsA";

  public ServiceASettings() {}
}

public class ServiceA : BaseService<ServiceASettings>, IService
{
  public ServiceA(ServiceASettings settings) : base(settings) 
  {
   Console.WriteLine(Settings.SettingA); // 现在可直接访问专属属性
  }
}

public class Program
{
  public static void Main(string[] args)
  {
    ServiceASettings settings = new ServiceASettings();
    ServiceA service = new ServiceA(settings);
  }
}

修改说明 #

1. 移除BaseSettings的泛型定义，将其改为普通抽象类，作为所有设置类的基类，保留共享设置属性
2. 将BaseService<T>中的Settings属性类型从BaseSettings<T>改为泛型参数T，同时构造函数参数也改为T
3. 派生设置类直接继承BaseSettings并实现ISettings接口

这样修改后，派生服务类中的Settings属性会直接对应到具体的派生设置类类型，无需强制转换即可访问专属属性。

内容的提问来源于stack exchange，提问作者Zerosum