gh-levnikolaevich-claude-code-skills-full-development-workflow-skills/skills/ln-341-code-quality-checker/references/yagni_violations.md

YAGNI Violations Reference

YAGNI (You Aren't Gonna Need It) principle: Don't add functionality until it's necessary.

Violation Patterns

1. Unused Functions/Classes

Violation:

def calculate_tax(amount):  # Defined but never called!
    return amount * 0.2

def process_payment(amount):
    return charge_card(amount)  # Doesn't use calculate_tax

Detection: Search codebase for function calls; if function never called → YAGNI violation

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2. Premature Abstraction

Violation:

# Interface with only ONE implementation
class UserRepositoryInterface:
    def get_user(self, id): pass
    def save_user(self, user): pass

class UserRepository(UserRepositoryInterface):  # Only implementation!
    def get_user(self, id):
        return db.query(User).get(id)
    def save_user(self, user):
        db.session.add(user)
        db.session.commit()

Fix: Remove interface until second implementation needed

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3. Over-Engineering

Violation:

# Complex pattern for simple problem
class UserFactoryBuilder:
    def __init__(self):
        self.strategy = None

    def set_strategy(self, strategy):
        self.strategy = strategy
        return self

    def build(self):
        return User(strategy=self.strategy)

# Usage
user = UserFactoryBuilder().set_strategy('default').build()

Fix:

# Simple solution
user = User()

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Version: 1.0.0 Last Updated: 2025-11-13