Question

I am subscribing to DispatcherOperation’s Completed event when the delegate finishes processing. Can any one please tell me how to get the value returned by the delegate inside the Completed event handler. I think it is only possible to not to block the main thread by accepting the return value inside the Completed event handler.

DispatcherOperation dispOp  = this.Dispatcher.BeginInvoke(balUpdater,
   GlobalParams._sessionObject.UserInfo.CardData);
dispOp.Completed += new EventHandler(dispOp_Completed);

void dispOp_Completed(object sender, EventArgs e)
{
   // accept return value of balUpdater here.
}

Answer 1

I would guess the sender parameter is quite possibly the DispatcherOperation, but if not, you can just capture the DispatcherOperation in a delegate:

DispatcherOperation dispOp  = this.Dispatcher.BeginInvoke(balUpdater,
   GlobalParams._sessionObject.UserInfo.CardData);
dispOp.Completed += (sender, args) => HandleCompletion(dispOp);

...


private void HandleCompletion(DispatcherOperation operation)
{
    object result = operation.Result;
    // Use the result here
}