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How Code Duplication Impacts Software Maintainability

How Code Duplication Impacts Software Maintainability

In many codebases across the software industry, code duplication is a common problem. Many projects have been deemed low-quality due to excessive duplication, and developers have expressed their dissatisfaction with the situation. This post explains everything you need to know about how code duplication impacts software maintainability and how and why it is a quality drain.

What Is Code Duplication?

Simply put, it occurs when a single line of code appears many times in a codebase. It occurs for a variety of reasons, such as when a developer wants to reuse a similar method in a different class and so ends up copy-pasting the code. Or when two people independently developed the same capability in two different places.

Code with similar capabilities is also considered as duplications. Irrespective of the reason, you end up having a similar code in two distinct places. When you expand a piece of code or correct a defect in it, you create unnecessary duplication of effort. People may think code duplication is fine, but it causes more problems for your product than you might think.

Must read: What is Duplicated Code

Why Is Code Maintainability Important?

The ability to write good quality, maintainable code is an important feature of the software. If the code quality is poor, it may result in financial losses or time waste as a result of maintenance, modification, and multiple changes. Efficiency, adaptivity, resilience, portability, maintainability, and readability are all characteristics of high-quality, maintainable code. Software performance and speed are directly related to efficiency.

Maintainability refers to developing code in such a way that it is simple to add new features, adjust existing features, or correct bugs with minimal effort and without disrupting other modules and functionalities. The software has a requirement for As a result, it is critical that the source code is simple to comprehend, determine what needs to be changed, make changes, and verify that the modifications do not bring any new problems. Following excellent new features and bug patches. coding practices, such as using suitable naming conventions for class names, methods, and variables can help to ensure maintainability ( ).

Reasons for non-recommendation of Code Duplication

To this date, one of the worst antipatterns in software engineering, code duplication leads to broken and unmaintainable systems. The following sections briefly discuss why:

Many programmers believe that there is no necessity to change code duplications if the software is working properly. You forget that you end up bulking your software unnecessarily. A strong argument that stands here is that running a few blocks of code takes only a few milliseconds.

Yes, but only if you intend to use your software a few times. Every minute, thousands or millions of times, code is created for commercial purposes. Every moment of delay causes further delay and increases the amount of space required on the user’s local workstation as well as on your servers.

Your software will run faster and take up less space if it has well-written code with few or ‘no’ duplications.

This is more of a copy-pasting programming issue than duplicate code, but it is worth mentioning because most people write repetitive code by copying and pasting. When someone plagiarizes code and incorporates it into their software, they overlook the holes and endings that the plagiarized code has. Attackers can exploit duplicate codes to gain access to your code, rendering it vulnerable.

It is fine to have duplication as long as you plan to discard your software quickly. To ensure that your software lasts a long time, it must have high-quality code. Duplicate code stinks up your code and adds to the technical debt associated with it.

The amount of capital and effort required to pay a developer to simplify or reduplicate this debt is the cost of repair. The decline in developer productivity has piqued due to the same.

Although it is often impossible to rework a duplicate code block, the goal should be to reduce technical debt as much as feasible. It aids in the improvement of the quality of your code.

How To Avoid Code Duplication Using Automated Code Review Tools Like Codegrip?

You may have concluded that duplicate code is bad for your software. However, how do you determine that your product has duplicate code? After all, it consists of numerous files with hundreds of lines of code in each. Unless there is only one file with a few lines of code, going over each line one by one does not appear to be a viable approach.

Automated tools are a great option in this situation. You may detect duplication in a matter of seconds with code review tools like Codegrip , regardless of the number of files or lines of code. Codegrip not only displays the duplication %, but also the file name, line number, and file location, and line number of the repeated code block.

Aside from duplication, Codegrip also displays flaws, code smells, security vulnerabilities, and code coverage.

Must read: How CodeGrip make code review easier for your organizations


Lack of understanding of a codebase is fatal when it comes to avoiding duplicate code. When you are given a coding task, you should take some time to familiarize yourself with the codebase before plunging in and typing code.

Investing some time in this now will pay dividends avoiding code duplication and ensuring code maintainability.

Originally published at on December 23, 2021.




Codegrip is helping 800+ Companies to Automate Your Code Review Process and develop better quality software.

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Pravin Uttarwar

Pravin Uttarwar

Helping companies to build quality software. A tech geek and community builder. Also a Chapter Director at StartupGrind.

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