clean-code-patterns

Clean Code Patterns

Clean code principles for Python. Code should read like well-written prose.

Triggers

Use this skill when:

• Code is hard to read or understand
• Function/class does too much
• Refactoring is needed
• Code review revealed issues
• Questions about SOLID, DRY, KISS

SOLID

More details: ${CLAUDE_PLUGIN_ROOT}/skills/clean-code-patterns/references/solid.md

S — Single Responsibility

# Bad — class does everything
class UserService:
    def create_user(self, data): ...
    def send_welcome_email(self, user): ...
    def generate_report(self, users): ...
    def export_to_csv(self, users): ...

# Good — each class = one responsibility
class UserService:
    def create_user(self, data): ...

class EmailService:
    def send_welcome_email(self, user): ...

class UserReportGenerator:
    def generate(self, users): ...
    def export_to_csv(self, users): ...

O — Open/Closed

# Bad — modify code when adding new type
def calculate_discount(order_type: str, amount: float) -> float:
    if order_type == "regular":
        return amount * 0.1
    elif order_type == "premium":
        return amount * 0.2
    elif order_type == "vip":  # Added new type — modified function
        return amount * 0.3

# Good — extend through new classes
from abc import ABC, abstractmethod

class DiscountStrategy(ABC):
    @abstractmethod
    def calculate(self, amount: float) -> float: ...

class RegularDiscount(DiscountStrategy):
    def calculate(self, amount: float) -> float:
        return amount * 0.1

class PremiumDiscount(DiscountStrategy):
    def calculate(self, amount: float) -> float:
        return amount * 0.2

# Add VIP — create new class, don't modify existing code
class VIPDiscount(DiscountStrategy):
    def calculate(self, amount: float) -> float:
        return amount * 0.3

L — Liskov Substitution

# Bad — subclass violates parent's contract
class Bird:
    def fly(self) -> None: ...

class Penguin(Bird):
    def fly(self) -> None:
        raise NotImplementedError("Penguins can't fly")  # LSP violation!

# Good — correct hierarchy
class Bird:
    def move(self) -> None: ...

class FlyingBird(Bird):
    def fly(self) -> None: ...

class Penguin(Bird):
    def move(self) -> None:
        self.swim()