如何在C＃3.5中取消异步委托？ [英] How can I cancel an asynchronous delegate in C# 3.5?

问题描述

我已经在Google上下搜索了，但是我几乎找不到有关该主题的任何适当信息。

I have searched google up and down but I can not find nearly any proper information about that topic.

我想做的是：

1. 用户在文本框中输入单个搜索字符串。


2. 我等待0.5秒，然后开始BeginInvoke我的代表


3. 如果用户再次键入一个字符，我想取消搜索并使用键入的新字符串开始新的搜索。


4. 不得阻止UI线程！

1. User types a single search-string in a textbox.
2. I wait 0.5 s then I start to BeginInvoke my delegate pointing to a search method.
3. If the user types again a char I want to cancel the Search and begin a new search with the new string typed.
4. The UI-Thread must not be blocked!

如何使用C＃3.5做到这一点？

How can I do that using C# 3.5 ?

更新：

查看：

private void OnTextChanged(...)
{
   if (SearchFormatEvent != null)
   {
       ICollection<object> collection = SearchFormatEvent("MySearchString");
       // Do stuff on the returned collection                            
    }
}

SearchProvider ：

// This is the delegate invoked for the async search taking the searchstring typed by the user
    public delegate ICollection<object> SearchInputTextStrategy<T>(string param);

    public class SearchProvider : ISearchProvider
    {
        private ITextView _view;
        private SearchInputTextStrategy<object> searchInputDelegate;

        public SearchProvider(ITextView view)
        {
            _view = view;
            _view.SearchFormatEvent += new ConstructSearchFormatDelegate(CostructSearchFormat);
        } 

        private string SearchFormat(string param)
        { 
            // compute string

            return string.Empty; //...
        }

        public ICollection<object> CostructSearchFormat(string param)
        {
            var searchfilter = SearchFormat(param);

             IAsyncResult pendingOperation = searchInputDelegate.BeginInvoke("searchfilter",null,null);

            // How can I cancel the Async delegate ?

            ICollection<object> result = searchInputDelegate.EndInvoke(pendingOperation);

            return result;                
        }
    }

推荐答案

切换到BackGroudWorker，它支持您所需要的一切（NoUI阻止，取消等，进度报告。。）

Switch to BackGroudWorker , is supports all you need ( NoUI Blocking , Cancellation ect, Progress Reporting..)

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