Gravity Is Getting Me Down

Posted on September 17, 2014

A lone astronaut floats out into space distraught
Gravity's a real downer.

I have encountered my first real roadblock in the coding world since starting ACLTC: Gravity. One of the prework assignments was to recreate a version of Connect Four that could be played on the console. But I can't get gravity to work.

We were instructed to use an array of arrays for the gameboard; easy enough. I was able to generate the gameboard and define methods to control the flow of turns.

I can get a piece to appear in the right spot when a player takes a first turn. But getting a piece to fall to the bottom after that is proving to be a sticky problem. And if it does fall properly, it has a tendency to overlap a piece that is already at the bottom, instead of stopping at the slot above.

I emailed Jay, the instructor, with my dilemma. He didn't give me the solution, but he did point me in the right direction. He suggested, instead of creating a method that replicated the advancement of a user's X through the gameboard in its logic, it work backwards, from the bottom up, checking first if the bottom space was occupied and moving up as needed.

With that in mind, I was able to come up with the following:

    def turn(board, prompt)

      puts prompt
      x = gets.chomp.to_i - 1
      y = 6 

      until board[y][x] != "X" || y == 0
        y -= 1

      if y < 0
        return turn(board, "Try again. Choose a different column 1-7.")
        board[y].insert(x, "X")
        puts "Good move!"


Nothing groundbreaking for sure -- my program isn't even the complete game -- but the salient point is this: A program doesn't need to replicate a real world analog; it just needs to look like it did. Code the easiest route, not the route closest to "realism." It's an important point that will keep you from trying to create the environment in which the wheel was invented so that you can reinvent it.