Euchre
A command-line implementation of the card game Euchre: card and pack modelling, trump and bower rules, and a game loop that runs hands to a target score. Computer and human players plug into the same abstract interface.
- Stack
- C++OOPPolymorphismUnit Testing
- Highlights
- Abstract Player interface with Simple (AI) and Human implementations
- Trump, left and right bower, and led-suit rules encoded in card ordering
- Unit tests covering cards, packs and player strategy
The problem
Euchre's rules make card comparison context-dependent. Which card wins depends on trump, on which suit was led, and on the bowers: the jack of the trump suit's partner colour becomes the second-highest trump. Getting that right everywhere is most of the work.
Approach
Rules in the card layer. Comparison helpers take trump and the led card into account, so higher-level code asks "does this card win?" rather than re-deriving the rules.
One interface, two kinds of player. A Player base class defines making
trump, discarding, leading and following. SimplePlayer implements a fixed
strategy; HumanPlayer prompts on the command line. A factory builds either
from the command-line arguments, so the game loop never knows which it has.
Tested layer by layer. Cards, packs and player strategy each have their own test suite, so the rules are checked before the game loop relies on them.