Dead code is the most overlooked aspect of software development projects. They can become common when they evolve. A large amount of dead code can be harmful to software.
The best way to ensure this is to detect dead code in the early stages to maintain the quality of the software application.
Let’s talk more about dead code below:
What is dead code?
Dead code can be referred to as the segment of code that is unnecessary for the software program. They are executed without their results being used or accessed.
Dead code is known as zombie code. Such a portion of code may have been part of earlier versions, experimental features, or functions that are no longer needed. If the dead code remains in the software, it can decrease the software’s efficiency and add unnecessary complexity to it. This can further make the code harder to understand and maintain.
Other types of dead code
Unreachable code
The segment of code that is never executed under any condition during program runtime. It could be due to conditional statements, loops, or other control flow structures. Besides this, the issue may even arise during development because of coding errors, incorrect logic, or unintended consequences of code refactoring.
Obsolete code
The portion of code that was once useful but not anymore. They have now become outdated or irrelevant due to changes in software requirements or function, technology, or best practices. Obsolete code may still be present in the codebase however, no longer recommended for use.
Orphaned code
Code that was once part of a functional feature or system but is now left behind or isolated. This can result from changes in project requirements, refactoring, feature removal, or other modifications in the development process. As obsolete code, this code may still be present but no longer integrated or contribute to the application functionality.
Commented out code
Sometimes, developers ‘comment out’ code rather than deleting it to use it in the future. However, when they forget about it, it can facilitate dead code. While it is a common practice, developers must take note of it otherwise it can reduce code readability and maintainability.
Why remove dead code?
Dead code majorly contributes to technical debt. While a small amount of technical debt is still fine, if it grows, it can negatively affect the team’s progress. This can also increase the delivery time to market to end-users and reduce customer satisfaction.
Hence, it is important to monitor technical debt through engineering metrics to take note of dead code as well.
Besides this, there are other reasons why removing dead code is crucial:
Improves maintainability
When dead code is present, it can complicate the understanding and maintenance of software systems. It can further lead to confusion and misunderstandings which increases the cognitive load of the engineering team.
Eliminating dead code lets them focus on relevant code that helps increase code readability, and facilitates feature updates and bug fixes.
Reduces security and risks
Dead code could be a hidden backdoor entry point to the system. This can be a threat to the security of the software. Moreover, dead code includes dependencies that are no longer needed.
Removing dead code simplifies code complexities, and improves code review and analysis processes. This further helps to address and reduce security vulnerabilities easily.
Decreases code and cognitive complexity
Dead code disrupts the understanding of codebase structure. It not only decreases the development process but also developers’ productivity and effectiveness.
Eliminating dead code results in reducing the overall size of the code. Hence, it makes it concise and easier to manage which potentially enhances developers’ performance.
Avoid code duplication
Duplicate code is a considerable strain on the software development process. However, when dead code is present, it diverts developers from identifying and addressing areas where code duplication occurs.
Hence, eliminating dead code avoids code duplication and improves the codebase’s quality.
Streamline development
When dead code is not present in the software, it allows developers to focus on the relevant active parts of the codebase. It also streamlines the process as there are no unnecessary distractions and identifies and addresses issues.
How to identify and remove dead code?
Static analysis tools
Dead code can often be removed through static code analysis tools. Automated tools such as code quality checkers can help in detecting unused variables, classes, imports, or modules. This allows developers to address and eliminate the dead code easily which reduces the development cost and improves the overall quality of the system.
However, the drawback is that during uncertainty regarding programming behavior, dead code may not be removed. Hence, static code analysis tools are not a complete solution.
Dynamic analysis tools
Dynamic code analysis tools involve running the program to see which lines are executed and identifying which code paths are never reached. Hence, the code that is never executed or used in the codebase i.e. dead code is eliminated.
However, most of these tools are specific to programming languages.
Version control history
Leverage version control systems such as GIT commits to identify code that was once active but now deprecated or replaced. Commits that were removed or modified could indicate areas where dead code be found.
In case of a mistake, the code can be retrieved from the version control system. Hence, less risky and easily manageable.
Refactoring
Through refactoring, developers carefully examine the codebase to identify sections that include unused or old code, unnecessary variables, functions, or classes. Hence, revealing dead code that can be safely removed. Moreover, refactoring aims to optimize code for performance, maintainability, and readability. This further allows developers to look out for inefficient or unnecessary code by replacing or redesigning these segments.
Code reviews
Code review is an effective method to maintain the quality of code. It promotes simplicity and clarity in the codebase. They can help in detecting dead code by applying best practices, standards, and conventions. However, when not automated, they can be time-consuming and harder to implement. Hence, it is recommended to use automated code review tools to speed up the process.
Typo - Automated code review tool
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Key features:
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Conclusion
In software engineering, detecting and removing dead code is imperative for streamlining the development process. You can choose the method or combination of methods to remove dead code that best aligns with your project’s needs, resources, and constraints.
All the best!
