Question

我想用许多APM风格的异步方法重用我的代码。每种方法都有一个BeginXXX和一个EndXXX签名对。我想在每个函数中重用相同的回调。

我一直使用下面的匿名方法，但我不确定如何将其提取为可重用的形式。我知道这应该很容易，但我无法弄清楚如何使用委托来实现这一点。（这就是我自学成才）

 var result = tableSymmetricKeys.BeginExecuteQuerySegmented(query, token, opt, ctx, (o) =>
                {
                    var response = (o.AsyncState as CloudTable).EndExecuteQuerySegmented(o);
                    token = response.ContinuationToken;
                    int recordsRetrieved = response.Results.Count;
                    totalEntitiesRetrieved += recordsRetrieved;
                    Console.WriteLine("Records retrieved in this attempt = " + recordsRetrieved + " | Total records retrieved = " + totalEntitiesRetrieved);
                    evt.Set();
                }, tableSymmetricKeys);

如何将(o) => ...的匿名方法提取到委托中并使其可重用？

Answer 1

您将创建一个包含所有“捕获”变量的类作为状态传递：

public class QueryState
{
   public CloudTable CloudTable{get;set;}
   public Token Token{get;set;}
   public class ManualResetEvent Evt{get;set;} //i'm guessing that's what this is
   //any other variables you were using
}

然后，您将创建一个这样的委托：

AsyncCallback asyncCallback = (asyncResult) =>
{
   QueryState state = asyncResult.State as QueryState;
   var response = state.CloudTable.EndExecuteQuerySegmented(asyncResult);
   //rest of method... make sure to use the state variable to get whatever you need.
}

最后，你这样称呼它：

var state = new QueryState
{
   CloudTable = tableSymmetricKeys,
   //set everything else
}

var result = tableSymmetricKeys.BeginExecuteQuerySegmented(query, token, opt, ctx,asyncCallback, state);

如何与许多APM BeginXXX呼叫共享AsyncCallback？

1 个答案: