Composition using Generic

Composition or inheritance. Composition is perferred way in OOP. Though there is drawback like repetitive code. With Generic in C#, repetitive code can be factored into a generic class.

First here is IPlayer, DrJekyll and BruceBanner.

public interface IPlayer
{
  stirng LiveIn { get; }
  string Play();
}

public class DrJekyll : IPlayer
{
  public string LiveIn { get { return "London"; } }
  public string Play() { return "Strolling around " + LiveIn + " cautiously"; }
}

public class BruceBanner : IPlayer
{
  public string LiveIn { get { return "New York"; } }
  public string Study { get { return "gamma ray"; } } 
  public string Play() { return "Playing with " + Study + " and trying not to get angry in" + LiveIn; }
}

And DrJekyll turns to MrHyde, BruceBanner to Hulk using inheritance. But inheritance ask to put 'virtual' on the original source code. It may not be possible.

public class DrJekyll : IPlayer
{
...
  public virtual string Play() ... 
}

public class MrHyde : DrJekyll 
{
  public override string Play() { return "Sneaking around " + LiveIn + " viciously"; }
}


public class BruceBanner : IPlayer
{
...
  public virtual string Play() ...
}

public class Hulk : BruceBanner 
{
  public override string Play() { return "Hate " + Study + " and rampage around " + LiveIn; }
}

Or composition can be used like below. MrHyde has OtherSelf DrJekyll and Hulk BruceBanner. Though notice the repetitive codes - OtherSelf, LiveIn.

public class MrHyde : IPlayer
{
  public DrJekyll OtherSelf { get; private set; } 
  public string LiveIn { get { return OtherSelf.LiveIn; } }

  public MrHyde( DrJekyll p ) { OtherSelf = p; }
  public string Play() { return "Sneaking around " + LiveIn + " viciously"; }
}

public class Hulk : IPlayer
{
  public BruceBanner OtherSelf { get; private set; } 
  public string LiveIn { get { return OtherSelf.LiveIn; } }

  public Hulk ( BruceBanner p ) { Self = p; }
  public string Play() { return "Hate " + OtherSelf.Study + " and rampage around " + LiveIn; }
}

The repetitive code can be bundled up to a generic class OtherSelf. Then MrHyde and Hulk only needs its own Play. And it can refer its Self for any property.

public abstract class OtherSelf< T > : IPlayer where T : IPlayer
{
  public T Self{ get; private set; }
  public PlayerBase( T otherSelf ) { Self = otherSelf; }
  public string LiveIn { return Self.LiveIn; }
  public abstract string Play();
}

public class MrHyde : OtherSelf< DrJekyll >
{
  public MrHyde( DrJekyll p ) : base( p ) {}
  public override string Play() { return "Sneaking around " + LiveIn + " viciously"; }
}

public class Hulk : OtherSelf< BruceBanner >
{
  public Hulk( BruceBanner p ) : base( p ) {}
  public override string Play() { return "Hate " + Self.Study + " and jumping around " + LiveIn; }
}

I didn't bother to check syntax on above code so please treat above as pseudo code.