C#

using System.Diagnostics;

//get info on current proc
Process proc = Process.GetCurrentProcess(); 
//get array of process w/ same name
Process[] procs = Process.GetProcessesByName(proc.ProcessName);            
//if there is more than one
if (procs.Length > 1)
    Application.Exit(); //exit
else
    Application.Run(new Form1()); //else run the app

f.propName = my vlaue;<br />
f.show();

public class MyClass
{
  public static event EventHandler Created;
  public MyClass()
  {
    // Initialize.
    // Fire static event.
    if (Created != null) Created(this, EventArgs.Empty);
  }
}

public class MyClass
{
  public MyClass()
  {
  }
  public event EventHandler MyEvent;
  protected virtual void OnMyEvent(EventArgs e)
  {
    if (MyEvent != null) MyEvent(this, e);
  }
}
public class MyClass2 : MyClass
{
  public MyClass2()
  {
  }
  protected override void OnMyEvent(EventArgs e)
  {
    // The EventArgs (or derived class) is passed so
    // that derived classes can check specific states.
    if (e != null) DoSomething();
    // Call the base class so that listeners can handle the event.
    base.OnMyEvent(e);
  }
}