Background Worker...how to kill the class??

[tyaz]

Hello! First Post!

I am a C# relative newbie; I picked up this code from MSDN:

*******************************************
class AreaClass2
{
public double Base;
public double Height;
public double CalcArea()
{
// Calculate the area of a triangle.
return 0.5 * Base * Height;
}
}

private System.ComponentModel.BackgroundWorker BackgroundWorker1
= new System.ComponentModel.BackgroundWorker();

private void TestArea2()
{
InitializeBackgroundWorker();

AreaClass2 AreaObject2 = new AreaClass2();
AreaObject2.Base = 30;
AreaObject2.Height = 40;

// Start the asynchronous operation.
BackgroundWorker1.RunWorkerAsync(AreaObject2);
}

private void InitializeBackgroundWorker()
{
// Attach event handlers to the BackgroundWorker object.
BackgroundWorker1.DoWork +=
new System.ComponentModel.DoWorkEventHandler(BackgroundWorker1_DoWork);
BackgroundWorker1.RunWorkerCompleted +=
new System.ComponentModel.RunWorkerCompletedEventHandler(BackgroundWorker1_RunWorkerCompleted);
}

private void BackgroundWorker1_DoWork(
object sender,
System.ComponentModel.DoWorkEventArgs e)
{
AreaClass2 AreaObject2 = (AreaClass2)e.Argument;
// Return the value through the Result property.
e.Result = AreaObject2.CalcArea();
}

private void BackgroundWorker1_RunWorkerCompleted(
object sender,
System.ComponentModel.RunWorkerCompletedEventArgs e)
{
// Access the result through the Result property.
double Area = (double)e.Result;
MessageBox.Show("The area is: " + Area.ToString());
}


*************************************************

I put the background worker code behind a form push button. So when I press the button I
get the result via the messagebox..fantastic...but press the button again, I get the result twice,
press it again, I get it three times...etc

Obviously the class I create with each push button still remains after worker completed, and thus I create an additional class with each button push.

How do I "kill" the class when backgroundworker worker completes? If I cant, how can I avoid creating a new class if I already have one from a previous button push...

Yes Newb questions, but thanks for your help.

[darwen]

Don't worry about creating a new instance every time. .NET will clean up automatically for you (that's what working in a managed language is all about).

You could always make the instance of the class a member variable and this will allow the background worker to reuse the instance. But beware ! If you ended up with multiple background workers (i.e. more than one thread at a time referencing the data) you hit concurrency issues and will have to start thinking about sychronising.

Synchronising sharing memory is a standard threading problem and if you're going to use threads I really recommend getting yourself familiar with them - it'll cause you so much less pain in future.

Darwen.

[Arjay]

In your button click call BackgroundWorker1.IsBusy to determine if you need to call RunWorkerAsync. Also, look at CancelAsync to cancel the current async operation (rather than killing or aborting the thread).