I apply best practices in designing this gem and each feature has had a LOT of thought put into it. Just look at how the Deck works. It's designed with an immutable set of cards to draw from and to return cards to. You can even seed it to write robust tests and get the same results time after time. Card evaluation is written in a functional way that allows, and is optimized for, lazy evaluation. The set verification is as simple as handing it some cards and the names of the rules to apply.

I'm willing to bet you that there is no other Ruby card game library out there as easy to use, as well thought out, and as simple to understand as mine. Come on, I dare you to use it and review it! ;-)

The scope of this project aims to be a game agnostic card management and evaluation system. Game logic itself will not be provided with this library. The creation, grouping, comparison, and evaluation of cards is the sole purpose of this gem.

Feel free to contribute or raise suggestions via the issue tracker. I welcome participation of all kinds! :-)

gem install 'cards_lib'

Requires Ruby 2 or greater.

Create a Card with Card.new(face)

CardsLib::Card.new("As")

Use a Macro to create a list of Card instances from card faces.

CardsLib::Cards["Ah","2h","3h","4h","5h"]

Create a Deck with Deck.new(cards) A default deck is generated if no parameters are given.

CardsLib::Deck.new

Pick what rules you'd like to use in determining a set of cards.

# BOOLEAN RESULT
CardsLib::IsSet.verify(
  card_instances_array,
  rules = [:unique, :ordered, :paired, :suited],
  specifications = {min: 3, max: Float::INFINITY}
)

• lib/cards_lib/is_set.rb is a golden tool in card hand verification.

• In lib/cards_lib/standard.rb there are some basic deck templates.

• In lib/cards_lib/standard/rules/poker_rule.rb there are some working Poker hand verification methods.

• In lib/cards_lib/standard/evaluators/blackjack_evaluator.rb there is a Blackjack hand worth evaluation tool. See the test/standard/evaluators/blackjack_evaluator_test.rb for examples.

The main difference between Rules and Evaluators is Rules are purposed for exact precedence and exact given matches (eg: two_pair only accepts 4 cards). An Evaluator can take all cards in a "Hand" (Hand is not yet defined in specification or implementation) and give a complete evaluation of the hands worth. To make a PokerEvaluator work for two_pair; one way you could implement it is with

hand.combination(4).detect {|cards| two_pair(cards)}

but this is a very inefficient way to implement this. Perhaps a more efficient way would be to use groupings

hand.group_by(&:rank).values.count {|group| group.length == 2} > 1

But that's pretty mutch the gist of it. The Evaluators can give the entire hand evaluation where-as Rules are specific scenarios.

Ranker is a card evaluation object that is passed into a Card when the Cards are first initialized. Each Card holds its own Ranker object.

include CardsLib
class CardRanks < Ranker
  def initialize(card)
    super card, "23456789TJQKA".chars
  end
end

deck = Deck.new ranker: CardRanks
# => <Deck: 52 Cards - Seed#317847827465261913302134114334103894430>

first_card = deck.pluck
# => (Card)
first_card.face
# => "Th"
second_card = deck.pluck
# => (Card)
second_card.face
# => "6h"

case [first_card.value, second_card.value].max
  when ->_{first_card.eql? second_card}
    puts "It's a tie!"
  when first_card.value
    puts "First player wins!"
  when second_card.value
    puts "Second player wins!"
  else
    raise "There was a problem determining a winner"
  end
end
# First player wins!

The example above shows the shorthand way of creating a Ranker object with passing the ranks as a simple list from least to greatest value. If you want to use a Hash (in case some cards of different ranks may be the same value) you may, but you must then also define a Proc for lookup. See lib/cards_lib/standard/rankers/blackjack_ranker.rb for an example of how to implement that.

The MIT License (MIT)

Copyright (c) 2015-2017 by Daniel P. Clark

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.