python-design-patternslisted

# Python Design Patterns Write maintainable Python code using fundamental design principles. These patterns help you build systems that are easy to understand, test, and modify. ## When to Use This Skill - Designing new components or services - Refactoring complex or tangled code - Deciding whether to create an abstraction - Choosing between inheritance and composition - Evaluating code complexity and coupling - Planning modular architectures ## Core Concepts ### 1. KISS (Keep It Simple) Choose the simplest solution that works. Complexity must be justified by concrete requirements. ### 2. Single Responsibility (SRP) Each unit should have one reason to change. Separate concerns into focused components. ### 3. Composition Over Inheritance Build behavior by combining objects, not extending classes. ### 4. Rule of Three Wait until you have three instances before abstracting. Duplication is often better than premature abstraction. ## Quick Start ```python # Simple beats clever # Instead of a factory/registry pattern: FORMATTERS = {"json": JsonFormatter, "csv": CsvFormatter} def get_formatter(name: str) -> Formatter: return FORMATTERS[name]() ``` ## Fundamental Patterns ### Pattern 1: KISS - Keep It Simple Before adding complexity, ask: does a simpler solution work? ```python # Over-engineered: Factory with registration class OutputFormatterFactory: _formatters: dict[str, type[Formatter]] = {} @classmethod def register(cls, name: str): de