access to modified closure 闭包的问题

自己的demo

 for (int i = 0; i < listBoxDevices.Items.Count; i++)
                {
                    var tempDeviceId = listBoxDevices.Items[i].ToString();
                    if (tempDeviceId.Contains("(掉线)"))
                    {
                        var id = GlobalConvert.GetDeviceID(tempDeviceId.Replace("(掉线)", string.Empty));
                        if (id == reonlineId)
                        {
                            listBoxDevices.Invoke((MethodInvoker)delegate
                            {
                                try
                                {
                                    listBoxDevices.Items[i] = GlobalConvert.GetDeviceID(reonlineId);
                                }
                                catch (Exception ex)
                                {
                                    ExceptionLog.Instance.WriteLog(ex, LogType.UI);
                                }
                            });
                        }
                    }
                }

代码里面有一个for循环

循环内部调用了匿名委托

模拟了一下：

但是下面这段代码的执行，不会出现问题是正常的

  private void button1_Click(object sender, EventArgs e)
        {
            Thread thread = new Thread(Closure);
            thread.IsBackground = true;
            thread.Start();
        }

        private void Closure()
        {
            for (int i = 0; i < 10; i++)
            {
                this.Invoke((MethodInvoker) delegate
                {
                    textBox1.AppendText(string.Format("{0}:{1}{2}", DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff"), i, Environment.NewLine));
                });
            }
        }

What are 'closures' in .NET?

I have an article on this very topic. (It has lots of examples.)

In essence, a closure is a block of code which can be executed at a later time, but which maintains the environment in which it was first created - i.e. it can still use the local variables etc of the method which created it, even after that method has finished executing.

The general feature of closures is implemented in C# by anonymous methods and lambda expressions.

Here's an example using an anonymous method:

using System;

class Test
{
    static void Main()
    {
        Action action = CreateAction();
        action();
        action();
    }

    static Action CreateAction()
    {
        int counter = 0;
        return delegate
        {
            // Yes, it could be done in one statement; 
            // but it is clearer like this.
            counter++;
            Console.WriteLine("counter={0}", counter);
        };
    }
}

Output:

counter=1
counter=2

Here we can see that the action returned by CreateAction still has access to the counter variable, and can indeed increment it, even though CreateAction itself has finished.