Programming Languages & Software 16 Jan 2008 05:19 am

Vis a tergo: Baseball cards as objects

Rob’s discussing object models for baseball cards. He is evolving a design bit-by-bit.

My first question is what use cases do you want for your database of baseball cards? Searching real stats for the season? Or just searching for cards? To me, that changes the way I’d lay it out.

To play along, here is a primitive set of plain old Ruby objects to model what he has so far. I thought it might be interesting to contrast the two.

OK, well, I lied, it is a little different, because I went ahead and subclassed for the variant card type.

class Card
  attr_reader :year, :number

  def initialize(number, year)
    @number = number
    @year = year
  end
end

class PlayerCard < Card
  attr_reader :player

  def initialize(number, year, player)
    super(number, year)
    @player = player
  end
end

class BattingLeadersCard < Card
  attr_reader :top_50_batting_players # this is a list of players

  def initialize(number, year, top_50_batting_players)
    super(number, year)
    @top_50_batting_players = top_50_batting_players
  end

  def top_3
	top_50_batting_players[0..2]
  end
end

class Player
  attr_reader :name, :team

  def initialize(name, team)
    @name = name
    @team = team
  end
end

Comments (3)

3 Responses to “Vis a tergo: Baseball cards as objects”

  1. on 16 Jan 2008 at 10:37 am 1.Kevin said …

    Do you have a test for that?

  2. on 16 Jan 2008 at 2:01 pm 2.Bob said …

    Why yes, I do.

    Here they are, with the suite first, all concatenated. Note, these are only positive tests, not negative cases, because this is just for fun.

    $:.unshift File.join(File.dirname(__FILE__),'..','lib')

require 'test/unit'
require 'player_test'
require 'card_test'
require 'player_card_test'
require 'batting_leaders_card_test'

##########
require 'test/unit'
require 'card'
require 'date'

class CardTest < Test::Unit::TestCase
  def test_ctor
    card = Card.new('1', Date.strptime("1968", '%Y').year)
    assert_equal('1', card.number)
    assert_equal(1968, card.year)
  end
end

require 'player'

class PlayerTest < Test::Unit::TestCase
  def test_ctor
    player = Player.new("Jimbo Smith", "Orioles")
    assert_equal("Jimbo Smith", player.name)
    assert_equal("Orioles", player.team)
  end
end

require 'player_card'
require 'date'

class PlayerCardTest < Test::Unit::TestCase
  def test_ctor
    player = Player.new("Jimbo Smith", "Orioles")
    card = PlayerCard.new('1', Date.strptime("1968", '%Y').year, player)
    assert_equal('1', card.number)
    assert_equal(1968, card.year)
    assert_equal("Jimbo Smith", player.name)
    assert_equal("Orioles", player.team)
  end
end

require 'batting_leaders_card'
require 'player'
require 'date'

class BattingLeadersCardTest < Test::Unit::TestCase
  def create_50_players
    players = []
    0.upto(49) { |index| players << Player.new("Jimbo Smith #{index}", "Orioles")}
    players
  end

  def test_top_3
    card = BattingLeadersCard.new('1', Date.strptime("1968", '%Y').year, create_50_players)
    assert_equal('1', card.number)
    assert_equal(1968, card.year)
    assert_equal(50, card.top_50_batting_players.size)
    top3 = card.top_3
    assert_equal(3, top3.size)
    top_1st, top_2nd, top_3rd = top3
    assert_equal("Jimbo Smith 0", top_1st.name)
    assert_equal("Orioles", top_1st.team)
    assert_equal("Jimbo Smith 1", top_2nd.name)
    assert_equal("Orioles", top_2nd.team)
    assert_equal("Jimbo Smith 2", top_3rd.name)
    assert_equal("Orioles", top_3rd.team)
  end
end

  3. on 16 Jan 2008 at 2:01 pm 3.Bob said …

    aaarrrgghh it took away the indentation

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