整个花活，用 模式匹配 + Record 模仿 Rust 的枚举：

// Service 里：
public record ServiceResult();
public record SuccessServiceResult(string Title, DateTime CreatedTime, int LikeCount) : ServiceResult;
public record FailedServiceResult(string ErrorMessage) : ServiceResult;

public ServiceResult ServiceMethod()
{
// 业务逻辑
}

// Controller 里：
public void ControllerMethod()
{
ServiceResult serviceResult = ServiceMethod();

serviceResult switch
{
SuccessServiceResult successResult => 处理成功的情况(),
FailedServiceResult failedResult => 处理失败的情况(),
};
}