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daily learnings as a ruby dev

Intro to Ruby & Web Dev: Tic-Tac-Toe OO Game

22 Sep 2014

Goal

Build a tic-tac-toe game with object oriented programming.

There are 2 Approaches

  1. Look at Procedural Code and extract classes and objects (more experienced)
  2. Write out psuedo code (put rules into words describing the game, list nouns and common verbs

Start with an empty 3x3 board.

Board with two players One player is "x", the other is "o", and player "x" goes first. Then they alternate until 3 of x/o in a row or all cells are ful, which means its a tie.

Extract Classes

Board

Square

you wouldn't want to say square is aware of position, b/c the square is no longer reusable - occupied? - mark(marker)

Game_engine

is the procedural peice to the game that will orchestrate the game Sequence of steps

  1. Draw a board
  2. Assign Player to "x"
  3. Assign Computer to "o" Loop until a winner or all squares are taken
  4. Player 1 picks an empty square Check for winner
  5. Player 2 picks an empty square
  6. Check for winner
  7. If there is a winner, show winner; else "It's a tie"
class Board
  WINNING_LINES = [[1,2,3], [4,5,6], [7,8,9], [1,4,7], [2,5,8], [3,6,9], [1,5,9], [3,5,7]]

  def initialize
    @data = {}
    (1..9).each {|position| @data[position] = Square.new(' ') }
  end

  def empty_squares
    @data.select {|_, square| square.empty?}.values
  end

  def empty_positions
    @data.select {|_, square| square.empty?}.keys
  end

  def all_squares_marked?
    empty_squares.size == 0
  end

  def three_squares_in_a_row?(marker)
    WINNING_LINES.each do |line|
      return true if @data[line[0]].value == marker && @data[line[1]].value  == marker && @data[line[2]].value == marker
    end
    false
  end

  def mark_square(position, marker)
    @data[position].mark(marker)
  end

  def draw
    system 'clear'
    puts
    puts "     |     |"
    puts "  #{@data[1]}  |  #{@data[2]}  |  #{@data[3]}"
    puts "     |     |"
    puts "-----+-----+-----"
    puts "     |     |"
    puts "  #{@data[4]}  |  #{@data[5]}  |  #{@data[6]}"
    puts "     |     |"
    puts "-----+-----+-----"
    puts "     |     |"
    puts "  #{@data[7]}  |  #{@data[8]}  |  #{@data[9]}"
    puts "     |     |"
    puts
  end
end

class Player
  attr_reader :marker, :name
  def initialize(name, marker)
    @name = name
    @marker = marker
  end
end

class Square
  attr_reader :value

  def initialize(value)
    @value = value
  end

  def empty?
    @value == ' '
  end

  def mark(marker)
    @value = marker
  end

  def to_s
    @value
  end
end

class Game
  def initialize
    @board = Board.new
    @human = Player.new("James", "X")
    @computer = Player.new("R2D2", "O")
    @current_player = @human
  end

  def current_player_marks_square
    if @current_player == @human
      begin
        puts "Choose a position #{@board.empty_positions} to place a piece:"
        position = gets.chomp.to_i
      end until @board.empty_positions.include?(position)
    else
      position = @board.empty_positions.sample
    end
    @board.mark_square(position, @current_player.marker)
  end

  def alternate_player
    if @current_player == @human
      @current_player = @computer
    else
      @current_player = @human
    end
  end

  def current_player_wins?
    @board.three_squares_in_a_row?(@current_player.marker)
  end

  def play
    @board.draw
    loop do
      current_player_marks_square
      @board.draw
      if current_player_wins?
        puts "The winner is #{@current_player.name}!"
        break
      elsif @board.all_squares_marked?
        puts "It's a tie."
        break
      else
        alternate_player
      end
    end
    puts "Bye"
  end
end

Game.new.play

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