Gems

What are gems?

Until now, all of our experiments have been quite straightforward. However, with two-dimensional arrays, we may have noticed the lack of visual cues. For example, the array for the “Sea Battle” game doesn’t look very intuitive in the console:

$ irb
> Array.new(10) { Array.new(10) }
 => [[nil, nil, nil, nil, nil, nil, nil, nil, nil, nil], [nil, nil, nil, nil, nil, nil, nil, nil, nil, nil], [nil, nil, nil, nil, nil, nil, nil, nil, nil, nil], [nil, nil, nil, nil, nil, nil, nil, nil, nil, nil], [nil, nil, nil, nil, nil, nil, nil, nil, nil, nil], [nil, nil, nil, nil, nil, nil, nil, nil, nil, nil], [nil, nil, nil, nil, nil, nil, nil, nil, nil, nil], [nil, nil, nil, nil, nil, nil, nil, nil, nil, nil], [nil, nil, nil, nil, nil, nil, nil, nil, nil, nil], [nil, nil, nil, nil, nil, nil, nil, nil, nil, nil]]

We still can understand what it is, but can we quickly find out the fifth row and second column? It would help if we ...