C#

using System;

public abstract class Test
{
    private Test()
    {
    }

    protected Test(string name)
    {
    }
}

public class Test2 : Test
{
    protected Test2(string name) : base(name)
    {
    }
}

public class MyForm : Form
{
  private static ArrayList instances = new ArrayList();
  public MyForm()
  {
    instances.Add(this);
  }
  protected override void Dispose(bool disposing)
  {
    instances.Remove(this);
    base.Dispose(disposing);
  }
  public static IList Instances
  {
    get { return instances; }
  }
}

foreach (MyForm form in MyForm.Instances)
  Console.WriteLine(form.Text);

string path = this.GetType().Assembly.Location;
path += ".config";

public static string ToSQL(object value)
{
	if (value == null)
		return "NULL";
 				
	if (value is string)
		return "'" + value.ToString().Replace("'", "''") + "'";
 				
	return value.ToString();
}