using System;
namespace DemoApp
{
    // This interface helps decouple the concept of
    // "writing output" from the Console class. We
    // don‘t really "care" how the Write operation
    // happens, just that we can write.
    public interface IOutput
    {
        void Write(string content);
    }
    // This implementation of the IOutput interface
    // is actually how we write to the Console. Technically
    // we could also implement IOutput to write to Debug
    // or Trace... or anywhere else.
    public class ConsoleOutput : IOutput
    {
        public void Write(string content)
        {
            Console.WriteLine(content);
        }
    }
    // This interface decouples the notion of writing
    // a date from the actual mechanism that performs
    // the writing. Like with IOutput, the process
    // is abstracted behind an interface.
    public interface IDateWriter
    {
        void WriteDate();
    }
    // This TodayWriter is where it all comes together.
    // Notice it takes a constructor parameter of type
    // IOutput - that lets the writer write to anywhere
    // based on the implementation. Further, it implements
    // WriteDate such that today‘s date is written out;
    // you could have one that writes in a different format
    // or a different date.
    public class TodayWriter : IDateWriter
    {
        private IOutput _output;
        public TodayWriter(IOutput output)
        {
            this._output = output;
        }
        public void WriteDate()
        {
            this._output.Write(DateTime.Today.ToShortDateString());
        }
    }
}