call an eventhandler with arguments

c# events handlers
dezkev picture dezkev · Sep 28, 2009 · Viewed 15.4k times · Source

Visual Studio 2008, C# 3.0.

I have a method below which calls an event handler. I would like to pass the two arguments received by the method to the event handler.

I would like to do something like this:

wc.DownloadDataCompleted += wc.DownloadedDataCompleted(strtitle, placeid);

Is this even possible, if yes, how would I go about doing it ?

Code Snippet:

public void downloadphoto(string struri,string strtitle,string placeid)
{
    using (WebClient wc = new WebClient())
    {
        wc.DownloadDataCompleted += wc_DownloadDataCompleted;
        wc.DownloadDataAsync(new Uri(struri));
    }
}

Answer

Jon Skeet picture Jon Skeet · Sep 28, 2009

The easiest way to do this is to use an anonymous function (an anonymous method or a lambda expression) to subscribe to the event, then make your method have just the parameters you want:

public void downloadphoto(string struri, string strtitle, string placeid)
{
    using (WebClient wc = new WebClient())
    {
        wc.DownloadDataCompleted += (sender, args) => 
            DownloadDataCompleted(strtitle, placeid, args);
        wc.DownloadDataAsync(new Uri(struri));
    }
}

// Please rename the method to say what it does rather than where it's used :)
private void DownloadDataCompleted(string title, string id, 
                                   DownloadDataCompletedEventArgs args)
{
    // Do stuff here
}

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