Simple Design Introduction Lecture 2: Handling Duplicate Code

Simple Design Roadmap

This lecture is the second lecture in the Simple Design series. You can view the Simple Design series at the following link: https://inf.run/VvwxD

It would be good to watch the first lecture (free lecture) first. https://inf.run/rpGb7

Course Syllabus

This lecture is the second in the Simple Design introduction series that covers methods for improving code quality. In the first lecture, we provided an overview of why Simple Design is proposed as a standard for code quality and what Simple Design is. The methods for achieving Simple Design can be summarized in the following two ways.

1. Remove duplicates from the code.

2. While reducing components to the minimum.

And this lecture focuses intensively on the first method of creating Simple Design: how to eliminate duplication in code. Specifically, it will cover the following content.

• Why is duplicate code bad, and how bad is it?

• Duplicate code is also a symptom of other design problems.

  
  

• Conditional Statement Duplication and Polymorphism

• Handling Slightly Different Duplicate Code

• Finding Hard-to-Detect Duplicates

• The problem of duplication between documentation and code

• Duplicate Code That's Okay to Leave Alone - Metric Tools, AI, etc.

  
  

We'll explore these concepts through the process of directly refactoring various example codes. The example code utilizes a mix of three languages: JavaScript, Python, and Java. Open source examples are also included.

These days, while AI has made development more convenient for coding, it's also causing many side effects, right? There are many cases where maintenance becomes more difficult due to the low-quality code that AI produces. However, AI can actually help create high-quality code. This course also covers how to utilize AI in beneficial ways.

You might think that code quality isn't important when you don't directly look at the code, like with vibe coding, but since AI also reads and writes code just like humans do, if the original code quality is poor, AI will also create bad code and generate many bugs. It also consumes much more tokens when writing code. In fact, code quality might become even more important in the AI era. So through this course, I hope you can reduce duplicate code and elevate your code quality to the next level.