🧠 Module 06: Software Design

Software design is about writing code that stays readable, changeable, and reliable as it grows. This module focuses on practical design principles you can apply daily — even in small scripts — to reduce bugs and make future changes easier.

Estimated Time: 6-8 hours
Prerequisites: Module 01 (Foundations), Module 04 (OOP Concepts), Module 05 (Functional Programming)
Level: ⭐⭐⭐ Upper-Intermediate

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📚 Topics Covered

#	Topic	Description	Key Concepts
01	DRY Principle	Remove duplication and centralize knowledge	duplication, single source of truth
02	KISS Principle	Prefer simple solutions that are easy to understand	simplicity, readability
03	YAGNI Principle	Build what you need now, not what you might need later	scope, overengineering
04	Separation of Concerns	Split responsibilities so each part has one job	layers, boundaries, modules
05	Coupling and Cohesion	Design for low coupling and high cohesion	dependencies, responsibility
06	Code Smells	Recognize warning signs of maintainability issues	long functions, god objects
07	Refactoring	Improve code structure without changing behavior	safe changes, small steps

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🎯 Learning Goals

By the end of this module, you should be able to:

• Spot duplication and apply DRY without over-abstracting.
• Choose simpler designs and explain why they’re safer.
• Avoid speculative features and premature abstractions (YAGNI).
• Organize code by responsibility using separation of concerns.
• Reduce coupling, increase cohesion, and understand trade-offs.
• Identify common code smells and propose concrete improvements.
• Refactor confidently using small, behavior-preserving steps.

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📂 Module Structure

06_software_design/
├── README.md
├── 01_dry_principle/
│   ├── README.md
│   ├── examples.py
│   ├── exercises.py
│   └── quiz.md
├── 02_kiss_principle/
│   ├── README.md
│   ├── examples.py
│   ├── exercises.py
│   └── quiz.md
├── 03_yagni_principle/
│   ├── README.md
│   ├── examples.py
│   ├── exercises.py
│   └── quiz.md
├── 04_separation_of_concerns/
│   ├── README.md
│   ├── examples.py
│   ├── exercises.py
│   └── quiz.md
├── 05_coupling_and_cohesion/
│   ├── README.md
│   ├── examples.py
│   ├── exercises.py
│   └── quiz.md
├── 06_code_smells/
│   ├── README.md
│   ├── examples.py
│   ├── exercises.py
│   └── quiz.md
└── 07_refactoring/
    ├── README.md
    ├── examples.py
    ├── exercises.py
    └── quiz.md

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Ready to start? Begin with 01_dry_principle!