CLR VIA C# 泛型的协变和逆变

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication6
{
class Program
{
public static ArgumentException FM(object s)
{
return new ArgumentException("aru");
}
static void Main(string[] args)
{
//逆变和协变
Func<object, ArgumentException> fn1 = FM;
Func<string, Exception> fn2 = fn1;
//里氏原则 Exception=ArgumentException 父类引用=子类对象的实例引用
Exception ret2= fn2("");
ArgumentException ret1= fn1("");
//ty的返回类型ArgumentException
var ty2 = ret2.GetType();

var ty1 = ret1.GetType();
//两个的实际类型都是System.ArgumentException
Console.WriteLine("ty1:"+ty1.ToString()+"\nty2:"+ty2.ToString());
Console.ReadKey();
}
}
}

原理图如下：