C# 2.0的新特色 第一部分

Anonymous Methods

public partial class Form1 : Form
{
  public Form1()
  {
    InitializeComponent();

    button1.Click += delegate(object sender, EventArgs e)
    {
      // The following code is part of an anonymous method.
      MessageBox.Show("You clicked the button, and " +
        "This is an anonymous method!");
    };
  }
}

在Java中有，看看就行了吧，当然在这个例子中还有了另一个新东西：partial。

Iterators

为了实现如下用法：

foreach (OrderItem item in catalog)
{
  // (Process OrderItem here.)
}

我们可以这样做：

Enumerator e = catalog.GetEnumerator();
while (e.MoveNext())
{
  OrderItem item = e.Current;
  // (Process OrderItem here.)
}

比如：

public class OrderCatalog
{
  private ArrayList orderItems = new ArrayList(); 

	public void Load()
  {
    // Fill collection for a test.
    orderItems.Clear();
    orderItems.Add(new OrderItem("Item 1"));
    orderItems.Add(new OrderItem("Item 2"));
    orderItems.Add(new OrderItem("Item 3"));
  } 

	public IEnumerator<OrderItem> GetEnumerator()
  {
    foreach (OrderItem item in orderItems)
    {
      yield return item;
    }
  }
}

public class OrderItem
{
  private string name;
  
  public string Name
  {
    get { return name; }
  } 

  public OrderItem(string name)
  {
    this.name = name;
  }
}

然后就可以这样用了：

OrderCatalog catalog = new OrderCatalog();
catalog.Load();
foreach (OrderItem item in catalog)
{
  MessageBox.Show(item.Name);
}

这是MSDN中的例子：

using System;
using System.Collections;
public class List
{
    public static IEnumerable Power(int number, int exponent)
    {
        int counter = 0;
        int result = 1;
        while(counter++ < exponent)
        {
            result = result * number;
            yield return result;
        }
    }

    static void Main()
    {
        // Display powers of 2 up to the exponent 8:
        foreach(int i in Power(2, 8))
            Console.Write("{0} ", i);
    }
}

Partial Classes

他可以让你把一个类放到两个文件中去。注意都得有关键字：partial
比如：

//在文件MyClass1.cs中
public partial class MyClass
{
  public MethodA()
  {...}
}

//在文件MyClass2.cs中
public partial class MyClass
{
  public MethodB()
  {...}
}