Introduction

This document is designed to help you practically learn design patterns by starting from common anti-patterns and exploring how to refactor them.
Rather than memorizing design patterns in isolation, the focus is on recognizing familiar structures, understanding the design issues they pose, and discovering viable refactoring options.

Chapter Structure

Each anti-pattern chapter follows a consistent structure:

1. Bad Example of the Anti-Pattern
   A concise example of a commonly seen structure along with its problems

2. Refactoring by Patterns
   Multiple refactoring solutions using relevant design patterns

3. Pattern Comparison
   Cross-pattern comparison of pros, cons, and appropriate vs. inappropriate use cases

4. Choosing the Right Pattern
   Decision-making criteria and structured heuristics for choosing a suitable pattern

5. Team Discussion Snippets Real-world conversational cues and questions for design reviews or implementation debates

6. Refactoring Task Practical exercises placed at the end of each chapter to reinforce pattern usage

Suggested Reading Styles

Reading Style	Description	Ideal For
Reference Use	Jump straight to relevant anti-patterns when needed	Real-world design/code reviews
Before/After Walkthrough	Explore refactoring examples and compare the code step-by-step	Developers learning through code
Exercise-First	Try the exercises first, then read the solutions	Readers who prefer hands-on learning
Pattern-Centric	Follow a specific design pattern across multiple chapters	Intermediate to advanced readers focused on mastery

Design Philosophy

• Train Structural Intuition
  The goal is to articulate "why this structure works" in your own words

• Focus on Structural Solutions, Not Just Pattern Names
  Emphasis is placed on understanding the structural nature of a solution, not just memorizing names

• Think Beyond Specific Languages
  Code examples are provided in multiple languages to highlight structural patterns over syntax

Use Cases

• As a guide for structuring design discussions and review meetings
• As a training material for onboarding or mentoring junior-to-mid-level engineers
• As a self-study workbook for improving design skills through refactoring