简单的委托学习

委托---->匿名表达式--->lambda表达式；这是一个进化的过程。

委托：就是用委托代替一个方法，实例化为一个类，就可以作为参数来使用。可进行+、-

MSDN：

public delegate void Del(string message);
// Create a method for a delegate.public static void DelegateMethod(string message){    System.Console.WriteLine(message);}
Del handler = DelegateMethod;// Call the delegate.handler("Hello World");

匿名方法：在委托的基础上，不用在写命名方法。直接给委托写上方法。

MSDN：

// Create a delegate.delegatevoid Del(int x);// Instantiate the delegate using an anonymous method.Del d = delegate(int k) { /* ... */ };Lambda：用表达式的形式使用匿名方法。先声明一个委托类，创建一个委托变量，对其进行赋值。可以说是变量和函数的结合吧。MSDN：
delegate int del(int i);static void Main(string[] args){    del myDelegate = x => x * x;    int j = myDelegate(5); //j = 25}

//a Test
delegate bool D();delegate bool D2(int i);class Test{    D del;    D2 del2;    public void TestMethod(int input)    {        int j = 0;        // Initialize the delegates with lambda expressions.        // Note access to 2 outer variables.        // del will be invoked within this method.        del = () => { j = 10;  return j > input; };        // del2 will be invoked after TestMethod goes out of scope.        del2 = (x) => {return x == j; };              // Demonstrate value of j:        // Output: j = 0         // The delegate has not been invoked yet.        Console.WriteLine("j = {0}", j);        // Invoke the delegate.        bool boolResult = del();        // Output: j = 10 b = True        Console.WriteLine("j = {0}. b = {1}", j, boolResult);    }    static void Main()    {        Test test = new Test();        test.TestMethod(5);        // Prove that del2 still has a copy of        // local variable j from TestMethod.        bool result = test.del2(10);        // Output: True        Console.WriteLine(result);                   Console.ReadKey();    }}