C#

public enum Shipper
    {
        UPS = 1,
        FedEx = 2,
        Purolator = 3
    }

    public interface IShip
    {
        void Ship();
    }

    public class ShipperPurolator : IShip
    {
        public void Ship()
        {
            //-- code logic to implement shipping method for Purolator
            MessageBox.Show("Purolator ship start");
        }
    }

    public class ShipperUPS : IShip
    {
        public void Ship()
        {
            //-- code logic to implement shipping method for Purolator
            MessageBox.Show("UPS ship start");
        }
    }

    public class ShipperFexEx : IShip
    {
        public void Ship()
        {
            //-- code logic to implement shipping method for Purolator
            MessageBox.Show("FedEx ship start");
        }
    }

    public class ShipperFactory
    {
        public static IShip CreateInstance(Shipper enumModuleName)
        {
            IShip objActivity = null;

            switch (enumModuleName)
            {
                case Shipper.UPS:
                    objActivity = new ShipperUPS();
                    break;
                case Shipper.FedEx:
                    objActivity = new ShipperFexEx();
                    break;
                case Shipper.Purolator:
                    objActivity = new ShipperPurolator();
                    break;
                default:
                    break;
            }
            return objActivity;
        }
    }

IShip objActivity = null;


        private void btnUPS_Click(object sender, EventArgs e)
        {
            objActivity = ShipperFactory.CreateInstance(Shipper.UPS);
            objActivity.Ship();
        }

        private void btnFedEx_Click(object sender, EventArgs e)
        {
            objActivity = ShipperFactory.CreateInstance(Shipper.FedEx);
            objActivity.Ship();
        }

        private void btnPurolator_Click(object sender, EventArgs e)
        {
            objActivity = ShipperFactory.CreateInstance(Shipper.Purolator);
            objActivity.Ship();
        }

var configFileName = AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;

_configuration = ConfigurationManager.OpenExeConfiguration(configFileName);

configFileName = configFileName.ToLower().Replace(".config", "");

private void LoadConfigFile()
{
    var configFileName = AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;

    // For some reason ConfigurationManager.OpenExeConfiguration adds ".config" to the end
    // of the file name, so it appears as "app.exe.config.config"
    configFileName = configFileName.ToLower().Replace(".config", "");

    _configuration = ConfigurationManager.OpenExeConfiguration(configFileName);

    AppConfigFile = configFileName;
}