CLI Blackjack

Features

• Multiple players
• Splitting
• Doubling down
• Variable # of decks
• Variable # of starting chips
• Killing process and resuming game via write ahead log

Playing

Requirements

• Ruby 1.9+
• Bundler

Install & Play

1. git clone git@github.com:KrisJordan/blackjack.git
2. cd blackjack
3. bundle install
4. ./blackjack

Run rspec tests

bundle exec rspec or guard for interactive, watch-based testing with guard.

Command-line Options

./blackjack --help to print command line options.

./blackjack --players=1 --decks=2 --chips=100

• players sets # of players in the game.
• decks sets # of decks in each round.
• chips sets # of chips each player starts with.

./blackjack --verbose resume a game and print all events resumed.

"Pausing" a Game

Break out of / pause a game at any point by interrupting with Ctrl+C or killing the process.

Resuming Game

To resume a game, rerun ./blackjack in the same directory and press y, or run with the --verbose flag.

Architectural Notes

The architecture of this project began with a few first principles, largely as an exercise to try them in a Ruby codebase:

• Immutability - All objects, with the exception of the top-level Game object, are immutable. All write accessors are copy-on-write.

• Event-driven - When state needs to change, an Event is emitted to the Game. The game then handles the Event by executing its #transform method. The Event#transform method accepts a Round and returns a new, transformed Round as effected by the Event. In essence: Event#transform(Round) -> Round'

• Write-ahead log - A nice side-effect of an event-driven architecture is that events can be logged to an append-only file and easily replayed to return a game to any state. The write-ahead log for this game is stored in your current working directory under .blackjack.aof. Its format is a simple, JSON serialization, that first serializes the Games initial state followed by a stream of Event objects transforming the game's state.

Codewalk, Top-down

• Primitives
• card.rb - the atom
• hand.rb - contains both cards in hand and chips riding on hand
• deck.rb - a stack of cards
• player.rb - a named holder of chips
• dealer.rb - a cold body
• High-level flow
• bin/blackjack.rb - command-line parser/runner
• game.rb - where mutable state of current players and round is kept, event loop runs here
• round.rb - immutable representation of a round at a point in time. Setters are copy-on-write.
• turn_iterator.rb - simple cursor for traversing the states, players, and hands of a round
• game_journal - the write-ahead logger/replayer
• Round States in state/
• betting.rb - players buy into the round
• dealing.rb - players receive a random card one at a time, run twice
• playing.rb - players move through each of their hand(s) until busting or passing
• paying.rb - players beating or pushing with the dealer are distributed chips
• ending.rb - round is over
• Events in event/
• base.rb - event base class with descriptions of methods
• bet.rb - player placed a bet
• skip.rb - noop skip turn (i.e. dealer's turn to bet)
• stand.rb - player ends turn
• hit.rb - be dealt another card, do not advance turn
• bust.rb - emitted when hand value exceeds 21
• double_down.rb - double bet on hand and receive 3rd, final card
• split.rb - split hand and put in more chips on second hand. Dealt a new card per hand.
• win.rb - reason and # of chips won by player event
• lose.rb - noop for printing narration
• end.rb - round is over

License

(The MIT License)

Copyright © 2014 Kris Jordan

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.