How do I pass an object into a timer event?

Question

Ok so I am using System.Timers.Timer in .Net 4 with C#.

I have my timer object like so:

var timer = new Timer {Interval = 123}; 

I have my Timer Elapsed event handler pointed at a method like so:

timer.Elapsed += MyElapsedMethod; 

And my method looks like this:

static void MyElapsedMethod(object sender, ElapsedEventArgs e) {     Console.WriteLine("Foo Bar"); } 

I want to pass a string into this method, how do I do this?

Thanks

Answer 1

The easiest way to do this is to change the event handler into an anonymous function. It allows you to pass the string at the point of declaration.

string theString = ...; timer.Elapsed += (sender, e) => MyElapsedMethod(sender, e, theString);  static void MyElapsedMethod(object sender, ElapsedEventArgs e, string theString) {   ... } 

Answer 2

If you want to be able to unregister your "Elapsed" event handler again, you shouldn't use a delegate without remembering it in a variable.

So another solution could be to create a custom class based on Timer. Just add whatever members you like and get your custom Timer object back from the "sender" argument of the "Elapsed" event handler:

class CustomTimer : System.Timers.Timer {     public string Data; }  private void StartTimer() {     var timer = new CustomTimer     {         Interval = 3000,         Data = "Foo Bar"     };      timer.Elapsed += timer_Elapsed;     timer.Start(); }  void timer_Elapsed(object sender, ElapsedEventArgs e) {     string data = ((CustomTimer)sender).Data; } 

This strategy of course works for other events and classes too, as long as the base class is not sealed.