namespace DesignPattern
{
    public interface ILogWriter
    {
        void Write(string target, string logValue);
    }
    public class TxtLogWriter : ILogWriter
    {
        ILogWriter Members

    }
    public class XmlLogWriter : ILogWriter
    {

        ILogWriter Members
    }
    public class DBLogWriter : ILogWriter
    {

        ILogWriter Members
    }


    public class Log
    {
        private ILogWriter m_logWriter;
        public Log(ILogWriter logWriter)
        {
            m_logWriter = logWriter;
        }
        public void Write(string target, string logValue)
        {
            m_logWriter.Write(target, logValue);
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            Log logTxt = new Log(new TxtLogWriter());
            logTxt.Write("TxtLogTarget", "TxtLogValue");
            Log logXml = new Log(new XmlLogWriter());
            logXml.Write("XmlLogTarget", "XmlLogValue");
            Log logDB = new Log(new DBLogWriter());
            logDB.Write("DBLogTarget", "DBLogValue");
            Console.ReadLine();
        }
    }
}