📝 Code Quality Guide¶

Overview¶

This guide outlines the code quality standards and practices for Alien Invasion.

Code Style¶

1. Python Style Guide¶

Follow PEP 8 with these additional rules:

# Use type hints
def move_ship(x: int, y: int) -> None:
    """Move the ship to specified coordinates."""
    ship.position = (x, y)

# Use dataclasses for data structures
@dataclass
class Position:
    x: float
    y: float

# Use enums for constants
class GameState(Enum):
    MENU = 1
    PLAYING = 2
    PAUSED = 3

2. Documentation¶

def fire_bullet(position: Position, direction: Vector2) -> Bullet:
    """Fire a bullet from the specified position.

    Args:
        position: Starting position of the bullet
        direction: Direction vector for bullet movement

    Returns:
        Bullet: The created bullet entity

    Raises:
        ValueError: If position is invalid
    """
    # Implementation

Code Organization¶

1. Directory Structure¶

src/
├── config/        # Configuration
├── core/          # Core systems
├── entities/      # Game entities
├── systems/       # Game systems
└── utils/         # Utilities

2. Module Organization¶

# module.py
"""Module docstring."""

# Imports
import pygame
from typing import List, Optional

# Constants
SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600

# Classes
class Game:
    """Game class docstring."""

    def __init__(self):
        """Initialize game."""
        pass

# Functions
def helper_function():
    """Helper function docstring."""
    pass

Best Practices¶

1. SOLID Principles¶

# Single Responsibility
class RenderSystem:
    def render(self, screen, entities):
        pass

# Open/Closed
class Weapon(ABC):
    @abstractmethod
    def fire(self):
        pass

class LaserWeapon(Weapon):
    def fire(self):
        pass

# Liskov Substitution
class Entity:
    def update(self):
        pass

class Ship(Entity):
    def update(self):
        pass

# Interface Segregation
class Movable(ABC):
    @abstractmethod
    def move(self):
        pass

class Drawable(ABC):
    @abstractmethod
    def draw(self):
        pass

# Dependency Inversion
class Game:
    def __init__(self, renderer: Renderer):
        self.renderer = renderer

2. Design Patterns¶

# Observer Pattern
class EventManager:
    def __init__(self):
        self.listeners = defaultdict(list)

    def subscribe(self, event_type, listener):
        self.listeners[event_type].append(listener)

# Factory Pattern
class EntityFactory:
    def create_ship(self, position):
        return Ship(position)

# Strategy Pattern
class MovementStrategy(ABC):
    @abstractmethod
    def move(self, entity):
        pass

Code Quality Tools¶

1. Static Analysis¶

# .flake8
[flake8]
max-line-length = 88
extend-ignore = E203
exclude = .git,__pycache__,build,dist

2. Type Checking¶

# mypy.ini
[mypy]
python_version = 3.8
warn_return_any = True
warn_unused_configs = True
disallow_untyped_defs = True

3. Formatting¶

# pyproject.toml
[tool.black]
line-length = 88
target-version = ['py38']
include = '\.pyi?$'

Testing Standards¶

1. Unit Tests¶

def test_ship_movement():
    ship = Ship()
    ship.move_right()
    assert ship.position.x == 5

def test_collision_detection():
    bullet = Bullet()
    alien = Alien()
    assert not check_collision(bullet, alien)

2. Integration Tests¶

def test_game_loop():
    game = Game()
    game.initialize()
    game.update(1.0)
    assert game.state == GameState.PLAYING

Code Review Checklist¶

1. General¶

2. Functionality¶

Works as intended
Handles edge cases
No side effects
Proper error handling

3. Performance¶

Efficient algorithms
No memory leaks
Reasonable complexity
Proper resource management

Common Issues¶

1. Code Smells¶

Long functions
Duplicate code
Magic numbers
Complex conditionals

2. Anti-patterns¶

God objects
Spaghetti code
Premature optimization
Over-engineering

Tools and Resources¶

1. Development Tools¶

Black: Code formatting
isort: Import sorting
flake8: Linting
mypy: Type checking
pytest: Testing

2. IDE Configuration¶

VS Code settings
PyCharm settings
Sublime Text settings

Next Steps¶

Read the Architecture Guide
Check out the Performance Guide
Learn about Testing