Best way to use System.ComponentModel.BackgroundWorker with lambda in C#

Question

I want to know the best way to do that:

using (var backgroundWorker = new BackgroundWorker())
{
    DoWorkEventHandler doWorkHandler = null;
    doWorkHandler = (s, e) =>
        {
            //Some expensive code goes here...
            backgroundWorker.DoWork -= doWorkHandler;
            //or
            //((BackgroundWorker)s).DoWork -= doWorkHandler;
        };
    backgroundWorker.DoWork += doWorkHandler;

    RunWorkerCompletedEventHandler workerCompleted = null;
    workerCompleted = (s, e) =>
        {
            //Update IU or something...
            backgroundWorker.RunWorkerCompleted -= workerCompleted;
            //or
            //((BackgroundWorker)s).RunWorkerCompleted -= workerCompleted;
        };
    backgroundWorker.RunWorkerCompleted += workerCompleted;

    backgroundWorker.RunWorkerAsync();
}

x

1. I imagine that I really need to remove the handler to avoid leak or something. Right?
2. Witch is the best, access the BackgroundWorker instance trought the "s" parameter or by the variable backgroundWorker?Is it the same?

Answer 1

There is no need to remove the handler, unless you are reusing the same BackgroundWorker instance somewhere else. However, given that you are surrounding it with a Using, this shouldn't be a problem (the scope of your worker is the using statement in this case).

Also, access to the backgroundWorker instance should work either way, however, when cycling data around I often like to use the userState instead which comes back in the RunWorkerCompletedEventArgs.