Question

I need to call a function using asynchronous delegates, when i go through the tutorial of the AsyncCallback I saw the async call back defined as below:

static void CallbackMethod(IAsyncResult result)
{
   // get the delegate that was used to call that
   // method
   CacheFlusher flusher = (CacheFlusher) result.AsyncState;

   // get the return value from that method call
   int returnValue = flusher.EndInvoke(result);

   Console.WriteLine("The result was " + returnValue);
}       

Please let me know if i can get the return value as reference from the function. eg:= my function is in the format

void GetName(int id,ref string Name);

Here i am getting the output from the function through a reference variable. If i call this function using the async delegates how can i read the output from the callback function?

Answer 1

You need to wrap your arguments into an object:

class User
{
    public int Id { get; set; }

    public string Name { get; set; }
}

void GetName(IAsyncResult result)
{
    var user = (User)result.AsyncState
    // ...
}

AsyncCallback callBack = new AsyncCallback(GetName);