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Implementing the OverCell and UnderCell Class

Implementing the OverCell and UnderCell Class

Learn about the implementation of tunneling by subclassing the Cell class with two different cell types: over-cells and under-cells.

We'll cover the following...

Walking through OverCell

The following is a start to our new OverCell class. We'll put it in weave_cells.rb later on.

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require 'cell'
class OverCell < Cell
  def neighbors
    list = super 
    list << north.north if can_tunnel_north? 
    list << south.south if can_tunnel_south?
    list << east.east   if can_tunnel_east?
    list << west.west   if can_tunnel_west?
    list
  end
end

Code explanation

Line 5: Calling super here gets us the default set of neighbors, as computed by our original Cell class. We then append to that list, adding potential targets to tunnel to.

Line 6: Here, we add the northern neighbor of this cell, as long as it is possible to tunnel north.

Next, we'll define the helper methods (can_tunnel_north? and friends). We'll add these after our new neighbours method.

The helper methods

The can_tunnel_north? and friends methods

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  def can_tunnel_north?
    north && north.north &&
      north.horizontal_passage?
  end
  def can_tunnel_south?
    south && south.south &&
      south.horizontal_passage?
  end
  def can_tunnel_east?
    east && east.east &&
      east.vertical_passage?
  end
  def can_tunnel_west?
    west && west.west &&
      west.vertical_passage?
  end

Here’s where we encode the logic that decides whether or not it’s even possible to tunnel in a given direction. Look at the ...