C＃如何传递的不仅仅是更多的IAsyncResult到的AsyncCallback？ [英] C# How do I pass more than just IAsyncResult into AsyncCallback?

问题描述

如何传递的不仅仅是更多的IAsyncResult到的AsyncCallback？

How do I pass more than just the IAsyncResult into AsyncCallback?

举例code：

//Usage
var req = (HttpWebRequest)iAreq;
req.BeginGetResponse(new AsyncCallback(iEndGetResponse), req);

//Method
private void iEndGetResponse(IAsyncResult iA, bool iWantInToo) { /*...*/ }

我想例如变量布尔iWantInToo 中传递。我不知道如何将它添加到新的AsyncCallback（iEndGetResponse）。

I would like to pass in example variable bool iWantInToo. I don't know how to add that to new AsyncCallback(iEndGetResponse).

推荐答案

您必须使用对象的状态，它传递，现在，你传递在 REQ 参数 - 但你可以，相反，通过在包含它和布尔值的对象。

You have to use the object state to pass it in. Right now, you're passing in the req parameter - but you can, instead, pass in an object containing both it and the boolean value.

例如（使用.NET 4的元组 - 如果你在​​.NET＆LT; = 3.5，则可以使用自定义类或KeyValuePair或类似）：

For example (using .NET 4's Tuple - if you're in .NET <=3.5, you can use a custom class or KeyValuePair, or similar):

var req = (HttpWebRequest)iAreq;
bool iWantInToo = true;
req.BeginGetResponse(new AsyncCallback(iEndGetResponse), Tuple.Create(req, iWantInToo));

//Method
private void iEndGetResponse(IAsyncResult iA) 
{
    Tuple<HttpWebRequest, bool> state = (Tuple<HttpWebRequest, bool>)iA.AsyncState;
    bool iWantInToo = state.Item2;

    // use values..
}

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