/// <summary>
/// 为了解决泛型父子类 关系的实例进行转换
/// 协变，逆变;只能放在接口或者委托的泛型参数前面
/// 协变：out
/// 只以做为返回值
/// 左边是父，右边是子
/// 逆变：in
/// 只可以做为参数值
/// 左边是子，右边是父
/// </summary>
public void Test()
{
{
parent parent1 = new parent();
parent parent2 = new child(); //父类拥有子类的所有属性
child child1 = new child();
}
{
List <Worker> parentlist1 = new List <Worker>();
//List<Worker> parentlist2 = new List<Worker>(); //两个list 泛型实例不存在集成关系
// 为解决两个父子关系的实例采用协变进行；
List <Worker> parentlist2 = new List <WorkBase>().Select(item => (Worker)item).ToList();
///协变 out 处理左侧是父，右侧是子
IEnumerable <WorkBase> outList = new List <Worker>();
IMyOut <WorkBase> outMyList = new MyOut <Worker>();
//逆变 in 处理左侧是子，右侧是父
IMyIn <Worker> inList = new MyIn <WorkBase>();
//协变+逆变
IMyInOut <Worker, WorkBase> myInOut = new MyInOut <WorkBase, Worker>();
//协变
IMyInOut <Worker, WorkBase> myInOut2 = new MyInOut <Worker, Worker>();
//逆变
IMyInOut <Worker, WorkBase> myInOut3 = new MyInOut <WorkBase, WorkBase>();
}
}
public static T Log <T>(T data, string id, string file, int line, int reason)
{
// Gather all the pending Console.Writes from the app, via our hooked side-effect Console.Out monoid
var s = MyOut.Log()?.Replace("\\", "\\\\").Replace("\r", "\\r").Replace("\n", "\\n");
if (s != null)
{
Queue.Post(new LineItem(file, line, $"\"{s}\""));
}
// Log this current event (for declarations and expression statements)
s = (id == null) ? "" : id + "=";
s += (data == null) ? "null" : data.ToString();
if (reason == 1 || reason == 2)
{
Queue.Post(new LineItem(file, line, s));
}
return(data);
}