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Writing Clean Code: 20 Code Smells and How to Get Rid of Them

Learn to identify and eliminate 20 critical code smells that plague software projects. Master the design principles and refactoring techniques that separate maintainable code from fragile, hard-to-change systems. Transform your development skills with hands-on training in writing code that scales.
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73 Lectures

Comprehensive Knowledge

6 Hours

Video Duration

20+ Labs

Focus on Practice

Course Certificate

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What you are going to learn

Build Code That Developers Actually Want to Maintain

This course teaches you to recognize and fix the patterns that make codebases hard to maintain, understand, and extend. Starting from core design principles and the SOLID framework, you will build the vocabulary and mental models needed to evaluate code quality objectively. Every concept is grounded in concrete before-and-after examples that show not just what to change, but why the change matters.

By the end of this course, you will be able to identify 20 of the most common code smells, apply targeted refactoring techniques to eliminate them, and reason clearly about design trade-offs. Whether you are writing new code or improving an existing codebase, you will have the skills to make deliberate, defensible decisions that your team will appreciate for years.

By completing this course, you will be able to:

  • Recognize and eliminate loops that hide complexity and obscure intent
  • Write meaningful comments that add value rather than duplicate information
  • Eliminate shotgun surgery by properly encapsulating internal structures
  • Consolidate duplicated knowledge into shared, well-designed modules
  • Create consistent abstractions across similar classes through common interfaces
  • Choose descriptive names that make code self-documenting
  • Replace primitive types with custom domain objects that enforce invariants
  • Split multitasking functions into focused, single-purpose components
  • Identify divergent change and restructure code to reduce reasons for modification
  • Simplify interfaces to hide internal complexity rather than expose it
  • Reduce long parameter lists through grouping and polymorphism
  • Avoid side effects by returning new data rather than mutating inputs
  • Eliminate middleman classes that add unnecessary indirection
  • Group related data into meaningful objects that encapsulate behavior
  • Replace repeated switch statements with polymorphic designs

Course Contents

Frequently asked questions

Who is this course designed for?

This course is designed for multiple technical roles and career stages.

Software Engineers and Developers who want to write better code and advance their careers will learn to recognize the subtle design issues that make code hard to change and maintain. You will gain practical techniques to refactor existing code and make better design decisions in new code from day one.

Technical Leads and Senior Engineers responsible for code quality will discover systematic approaches to mentor junior developers, establish code standards, and recognize when architectural decisions create unnecessary complexity. You will understand not just what good design looks like but how to communicate why poor design matters to your team.

Software Architects and Technical Stakeholders evaluating code quality and maintainability will gain the vocabulary and frameworks to assess codebases, identify structural problems, and guide refactoring efforts. You will understand how design decisions early in a project compound over time.

Developers Transitioning to New Roles who want to succeed in positions with higher technical expectations will build the foundational knowledge required to work effectively in teams with strong engineering standards.

What prior knowledge do I need before taking this course?

You should have practical experience writing code in any object-oriented or functional programming language. Basic familiarity with concepts like classes, functions, interfaces, and inheritance will help you follow the examples.

No prior knowledge of design patterns, SOLID principles, or software architecture is required. The course builds your knowledge from the ground up, starting with foundational concepts and progressing through increasingly sophisticated design challenges.

How are the code examples structured so I can follow along?

Each code smell is presented in three parts. First, you see the problematic code and understand the issues it creates. Second, you learn the specific refactoring techniques to fix the problem. Third, you see the improved code and understand why it is better.

The course uses Git branches to organize examples. You can check out different branches to see before-and-after versions of code, making it easy to compare changes and understand the transformation. The repository includes clear instructions on navigating the examples using standard Git commands and IDE features.

Will I be able to refactor existing code with these techniques?

Yes, absolutely. The refactoring techniques covered in this course are designed to be practical and applicable to existing systems. You will learn how to improve code incrementally without requiring a complete rewrite.

Each section includes concrete refactoring steps that show exactly how to move from problematic code to improved code. You will understand how to identify the scope of changes needed and how to refactor safely in a way that maintains functionality while improving design. These are the same techniques used by professional development teams to gradually improve their codebases while continuing to deliver features.