At first i was not very fond of LINQ but it seems that i am finally convinced that LINQ may improve readability:

bool IsCompleted()
{
 var boxesNotOnGoal = from cell in Cells
                      where cell.HoldsBox() && !cell.IsGoal()
                      select cell.Piece;

 return boxesNotOnGoal.Any();
}

Currently i am implementing Sokoban and i was pondering which methods i should add to my Cell class:

• bool HoldsWall
• bool HoldsBox
• bool HoldsPlayer

Or

• bool HoldsPieceOfType(Type type)

Which option should i choose? With the aid of extension methods (in the same namespace) i can have them both:

namespace Sokoban.Domain
{
 public static class ExtensionMethods
 {
  public static bool HoldsBox(this Cell cell)
  {
   return cell.HoldsPieceOfType(typeof(Box));
  }

  public static bool HoldsPlayer(this Cell cell)
  {
   return cell.HoldsPieceOfType(typeof(Player));
  }

  public static bool HoldsWall(this Cell cell)
  {
   return cell.HoldsPieceOfType(typeof(Wall));
  }
 }
}

In case you don’t like this solution, blame Brad Abrams who inspired me to implement it this way with his session at Visug yesterday.

Remark: Because the possible pieces in Sokoban are very well known (the game/requirements are not going to change) thus one should choose the first option (No extension methods required.)