static void Main(string[] args)
{
Calculate cal = Add;
Console.WriteLine(cal(5, 5));
Calculate cal1 = Mutiply;
Console.WriteLine(cal1(8, 8));
Console.ReadLine();
Del d = MethodOne;
d += MethodTwo;
d();
int invocationCount = d.GetInvocationList().GetLength(0);
Console.WriteLine(invocationCount);
CovarianceDel Cov = null;
Cov = MethodStream;
Cov = MethodString;
Console.ReadLine();
}
static void Main(string[] args)
{
//Because MethodStream and MethodString inherit from Text write you can use
//del with both methods. This is covariance;
del = MethodStream;
del = MethodString;
}
// covariance with delegates (objects that inherit from the same thing)
public static void Main(string[] args)
{
CovarianceDel del = MethodStream;
del += MethodString;
del();
Console.ReadKey();
}
public static void Test_CovarianceDel()
{ // you can assign both methods to del
del = MethodStream;
del();
del = MethodString;
del();
Console.ReadLine();
}
static void Main(string[] args)
{
MaineCoon mc = new MaineCoon("Чейз");
CovarianceDel del = mc.GetMaineCoonCat;
Cat cat = del();
Console.WriteLine(cat.Name);
Console.WriteLine(cat.Breed);
Console.ReadKey();
}
public void DoTest()
{
// both return class inherits from TextWriter
// 共変性(covariance)
del = MethodStream;
del = MethodString;
// parameter StreamWriter also inherits TextWriter
// 反返性(contravariance)
contraDel = DoSomething;
Func <int, int, int> calc = (x, y) => x + y;
Console.WriteLine($"Func<int, int, int> calc = {calc(1, 2)}");
}
static void Main(string[] args)
{
CovarianceDel d = GetInfo;
Console.WriteLine("Covariance.... !!");
Console.Write(d().Age); //Covariance : Able to call method with return type is derived form which is defined by delegate
Console.ReadLine();
Console.WriteLine("Contravariance.... !!");
Employee emp = new Employee()
{
Age = 23, CompanyName = "Acme Inc"
};
ContraDel c2 = PrintEmp;
c2(emp);
Console.ReadKey();
}
public void Ex3_Covariance()
{
CovarianceDel del = MethodCovar;
Base d = del(); // returns delegate type
}
