PrototypePattern

main.dart

//#region Plain Maze
enum Direction {
	North,
	West,
	South,
	East
}

class Maze {
	List<Room> rooms = [];

	void addRoom(Room room) {
		rooms.add(room);
	}
}

// Basically an interface
abstract class RoomSide {
  RoomSide clone();
}

class Wall implements RoomSide {
  Wall clone() {
    return Wall();
  }
}


class Door implements RoomSide {
	Room room1;
	Room room2;

	Door(this.room1, this.room2);
  
  Door clone() {
    // Shallow-copy
    return Door(room1, room2);
  }
}

class Room {
	Map<Direction, RoomSide> sides = {};

	void setWall(Direction direction, RoomSide side) {
		sides[direction] = side;
	}
  
}

class MazeFactory {
	Maze createMaze() => Maze();
	Wall createWall() => Wall();
	Room createRoom() => Room();
	Door createDoor(Room room1, Room room2) => Door(room1, room2);
}
//#endregion

//#region Strengthened Maze
class StrengthenedDoor extends Door {
	StrengthenedDoor(room1, room2) : super(room1, room2);
  Door clone() => StrengthenedDoor(room1, room2);
}

class StrengthenedWall extends Wall { 
  int strength;
  StrengthenedWall({this.strength}) : super();
  Wall clone() {
    return StrengthenedWall(strength: strength);
  }
}

class StrengthenedMazeFactory extends MazeFactory {
	Wall createWall() => StrengthenedWall();
	Door createDoor(Room room1, Room room2) => StrengthenedDoor(room1, room2);
}
//#endregion

//#region Spellbound Maze
class SpellboundDoor extends Door { 
	SpellboundDoor(room1, room2) : super(room1, room2);
}
class SpellboundMazeFactory extends MazeFactory {
	Door createDoor(Room room1, Room room2) => SpellboundDoor(room1, room2);
}
//#endregion

//#region MixMatch
class MixMatchFactory extends MazeFactory {
  Door prototypeDoor;
  Wall prototypeWall;
  
  MixMatchFactory({
    this.prototypeDoor,
    this.prototypeWall,
  }) : super();
    
  @override
  Wall createWall() => prototypeWall.clone();
	@override
	Door createDoor(room1, room2) {
    Door door = prototypeDoor.clone();
    door.room1 = room1;
    door.room2 = room2;
    return door;
  }
}

final testMixMatchFactory = MixMatchFactory(
  prototypeDoor: SpellboundDoor(null, null),
  prototypeWall: StrengthenedWall(strength: 100),
);
//#endregion