using System;
using System.Threading;

//不需要建構函式的委託物件
internal sealed class NoConstructorDelegateClass
{
    public static void CallbackWithoutNewingADelegateObject()
    {
        ThreadPool.QueueUserWorkItem(SomeAsyncTask, 5);
    }

    private static void SomeAsyncTask(Object o)
    {
        Console.WriteLine(o);
    }
}

//不需要定義回撥方法,生成一個一個靜態委託欄位，並在呼叫時例項化
internal sealed class NoCallbackMethodDelegateClass
{
    public static void CallbackWithoutNewingADelegateOjbect()
    {
        ThreadPool.QueueUserWorkItem(delegate(Object obj) { Console.WriteLine(sm_name + obj); },5);
    }
}

//不需要指定回撥方法的引數
internal sealed class NoCallbackMethodAndParametersDelegateClass
{
    public static void CallbackWithoutNewingADelegateOjbect()
    {
        ThreadPool.QueueUserWorkItem(delegate{ Console.WriteLine("Test"); }, 5);
    }
}

//不需要將區域性變數人工封裝到類中，即可將它們傳給一個回撥方法 自動生成輔助類
internal sealed class NoEnLocalVarToClassDelegateClass
{
    public static void UsingLocalVariablesInTheCallbackCode(Int32 numToDo)
    {
        Int32[] squares = new Int32[numToDo];
        AutoResetEvent done = new AutoResetEvent(false);

        for (Int32 n = 0; n < squares.Length; n++)
        {
            ThreadPool.QueueUserWorkItem(delegate(Object obj)
            {
                Int32 num = (Int32)obj;
               
                squares[num] = num * num;

                if (Interlocked.Decrement(ref numToDo) == 0)
                    done.Set();
            }, n);
        }

        done.WaitOne();

        for (Int32 n = 0; n < squares.Length; n++)
        {
            Console.WriteLine("Index {0},Square = [1]",n,squares[n]);
        }
    }
}