Refactoring vs. Rewriting Legacy Code

At some point in the world of software development, you will face the decision of whether to refactor your code or rewrite it entirely. Refactoring involves making small changes to improve the internal structure of the code without affecting its external behavior. 

On the other hand, rewriting code means starting fresh and creating an entirely new codebase while retaining the same or similar functionality. Both options have their pros and cons, and the choice between them depends on various factors, including the type of application, your team’s capabilities, project goals, and risk tolerance level.

Advantages of Refactoring Code

The practice of refactoring code emerges as a crucial endeavor to maintain and enhance the quality of existing software systems. By systematically restructuring code without altering its external behavior, refactoring brings forth numerous benefits, from improving code readability and maintainability to enhancing overall system scalability and extensibility.

• Improved Maintainability: Refactored code is typically easier to understand and maintain. The clean and organized code structure allows developers to quickly identify and fix issues, reducing the time and effort required for future maintenance tasks.
• Code Quality Enhancement: Refactoring code helps you identify and eliminate code smells, such as duplicated code or complex functions. This process leads to cleaner, more efficient code that is easier to test and less prone to bugs.
• Cost-Effective Solution: Refactoring can improve your application without the need to start from scratch. It is a more cost-effective option compared to rewriting the entire codebase, as it allows you to gradually improve the code while retaining the functionality and avoiding the risks associated with a complete rewrite.

Disadvantages of Refactoring Code

While refactoring code has many benefits, there are some potential disadvantages to consider.

• Refactoring can be time-consuming and demands skill, discipline, and courage from developers.
• It may not address underlying architectural issues and does not inherently provide avenues for integrating new functionalities into an application.
• Refactoring can lead to an increase in code volume, necessitating additional management and unit testing efforts, particularly when complex functions are broken down into simpler ones.
• In instances where the codebase requires substantial architectural alterations, opting for a rewrite may prove to be a more appropriate solution.

Advantages of Rewriting Code

Rewriting code offers numerous benefits that can greatly impact your software project. By starting with a clean slate and making foundational changes to the code, you can set your project up for long-term success. Here are some advantages of rewriting code:

• Opportunities for Growth: Rewriting code allows you to embrace new market opportunities and adapt to emerging technologies. It enables you to stay competitive and meet the evolving needs of your users.
• Improving Performance: Through a complete rewrite, you can optimize your codebase for better performance and efficiency. This can result in faster load times, reduced resource consumption, and an overall improved user experience.
• Eliminating Outdated Technologies: Rewriting code gives you the chance to eliminate outdated technologies and legacy code that may be holding your project back. It enables you to leverage modern tools and frameworks, reducing technical debt. According to industry statistics, companies pay an additional 10 to 20 percent to address tech debt on top of the costs of any project. By proactively addressing technical debt through code rewriting, you can mitigate these extra costs and ensure the long-term viability and efficiency of your project.
• Code You’re Comfortable With: When you rewrite the code, you have the freedom to implement coding standards and practices that you are comfortable with. This can boost developer productivity and satisfaction.
• Motivation for the Team: A complete rewrite can be a motivating factor for your development team. It provides them with new challenges and the opportunity to showcase their skills in creating a robust and efficient codebase.

Disadvantages of Rewriting Code

While rewriting code has its advantages, it also comes with several disadvantages that need careful consideration before making the decision to embark on a complete rewrite.

• Time-consuming process: Rewriting code is a time-intensive task that can significantly extend project timelines. It requires a thorough understanding of the existing codebase and careful planning to ensure all functionalities are correctly translated to the new code.
• Resource-intensive: A complete code rewrite demands substantial effort and resources. It can strain development teams as they navigate the challenge of maintaining the old code while simultaneously creating the new one.
• Potential introduction of new defects: Rewriting code carries the inherent risk of introducing new defects into the system. Despite rigorous testing, it is common for new bugs and unexpected issues to arise during the rewriting process.
• Increased complexity: The act of rewriting code may inadvertently introduce additional layers of complexity. Poorly planned or executed rewrites can make the codebase even more intricate, hindering future maintenance and improvements.
• No guarantee of improvement: While a complete code rewrite may seem like an opportunity for improvement, it does not guarantee that the new code will be better than the old one. In some cases, it may even fail to address the underlying issues or meet the intended goals.
• Disruption to development workflows: Undertaking a complete code rewrite can disrupt existing development workflows, potentially impacting productivity and causing delays in project delivery.

In summary, while rewriting code may seem like an appealing option to address certain issues, it is essential to weigh the disadvantages against the potential benefits. An informed decision should be made based on the specific circumstances, project goals, resources available, and the overall impact on the development process.

When to Rewrite instead of Refactor

Deciding whether to refactor existing code or rewrite it from scratch is a significant strategic choice that can impact the project’s timeline, cost, and future maintainability. While refactoring involves modifying the internal structure of the code without changing its external behavior, rewriting entails creating the application anew, which can address deeper issues but also introduce more risk. Here are key scenarios when rewriting might be preferred over refactoring:

• Technological Obsolescence: When the current technology stack is outdated and no longer supported, a rewrite allows the adoption of modern frameworks, languages, and tools that enhance performance, security, and developer productivity.
• Fundamental Architecture Issues: If the existing system suffers from deep-rooted architectural flaws that cannot be efficiently resolved through incremental refactoring, a rewrite might be necessary. This includes problems like poor scalability, security vulnerabilities, or a mismatch with current business needs.
• Codebase Understandability and Maintainability: Over time, a codebase may become so complex and convoluted that understanding and maintaining it is more costly than rebuilding it. A rewrite can simplify the code, making it more understandable and easier to maintain.
• Changing Business Goals or Directions: Significant shifts in business strategy or objectives might render the current application misaligned with organizational needs. A rewrite can realign the software with the new direction, incorporating features and capabilities that support the evolved goals.
• Performance and Efficiency Gains: When performance bottlenecks are fundamentally tied to the existing architecture, and refactoring cannot address these issues without extensive changes, a rewrite can offer a path to achieve the necessary performance and efficiency improvements.
• Cost-Benefit Analysis: Sometimes, the effort and resources required to refactor an application, especially if it’s large and complex, might exceed those needed for a rewrite. If a cost-benefit analysis shows that a rewrite is more economical in the long run, considering both direct costs and opportunity costs, it might be the preferred approach.

Considerations Before Deciding to Rewrite:

• Risk Assessment: Rewrites carry significant risks, including project delays, budget overruns, and the potential loss of critical functionality. Thoroughly assess these risks before proceeding.
• Incremental Approach: Consider whether a hybrid approach is feasible, where the system is gradually rewritten in parts, allowing for risk mitigation and continuous delivery of value.
• Stakeholder Buy-in: Ensure that all stakeholders understand the reasons for the rewrite, the expected benefits, and the projected costs and timelines.

Choosing to rewrite instead of refactor is a major decision that should be made with careful consideration of the specific context, challenges, and objectives of your project. It requires a strategic approach, thorough planning, and clear communication across the entire team and stakeholders.

When to Refactor Instead of Rewrite

Refactoring is the process of restructuring existing computer code without changing its external functionality. It is a crucial strategy for improving code readability, reducing complexity, and enhancing maintainability. Here are key situations when refactoring is preferred over a complete rewrite:

• Maintaining Business Continuity: When the application is critical to daily operations, and downtime needs to be minimized, refactoring allows for incremental improvements without disrupting the service.
• Cost and Resource Constraints: Refactoring is generally less resource-intensive than a full rewrite. It can be a more viable option when budget and developer resources are limited, allowing for gradual enhancements.
• High-Quality Existing Codebase: If the codebase is fundamentally solid but has areas that need optimization or updating, refactoring can address these issues without discarding the valuable existing work.
• Learning and Knowledge Retention: Refactoring allows developers to deepen their understanding of the codebase and the application’s functionality. It facilitates knowledge retention and transfer within the team.
• Risk Management: Refactoring reduces the risk associated with introducing bugs or losing functionality, as changes are made incrementally and can be tested more thoroughly.
• Incremental Improvement: When the goal is to continuously improve the codebase while adding new features or adhering to new standards, refactoring allows for ongoing enhancements without a complete overhaul.
• Compatibility and Integration Needs: In cases where the application needs to remain compatible with other systems or specific technologies, refactoring can update or improve the system while ensuring it continues to integrate smoothly with its ecosystem.

Considerations Before Deciding to Refactor:

• Scope and Scale: Understand the scope of the needed changes. If the refactoring is too extensive, it might approach the effort of a rewrite. Ensure that the scope of refactoring is manageable and justified.
• Regression Testing: Implement comprehensive testing to ensure that refactoring does not alter the application’s functionality. Automated tests can facilitate this process.
• Documentation: Keep documentation updated with the changes. Refactoring can significantly alter the structure and organization of the code, making up-to-date documentation critical for ongoing maintenance.

Refactoring is an effective strategy for enhancing the quality of a codebase with minimal disruption. It leverages the existing investment in the code while making it more maintainable, efficient, and adaptable to future needs. Choosing to refactor requires a careful assessment of the codebase’s condition, the project’s objectives, and the specific improvements needed to meet those goals.

Conclusion

In the ongoing debate of whether to rewrite or refactor your software, there is no one-size-fits-all answer. Each approach has its pros and cons, and the decision ultimately depends on the specific needs and context of your software project.

Refactoring code offers the advantage of incremental improvements and cost-effectiveness. It allows for enhancing maintainability, code quality, and collaboration among team members. By making small changes to original code, you can achieve better code readability and easier maintenance, without the need for a complete overhaul.

On the other hand, rewriting your code provides an opportunity for a fresh start. It allows for addressing fundamental issues and embracing new technologies. With a complete overhaul, you can achieve scalability, improved performance, and alignment with your business objectives.

When making the decision to refactor or rewrite your application, it’s crucial to consider your project goals, budget, available resources, impact on users, technical debt, and strategic vision. By carefully weighing these factors, you can make an informed choice that ensures the long-term success and viability of your software project.

If you need help with your software development project, read more about Flatirons’ custom software development services.

FAQ

What is the difference between refactoring and rewriting legacy code?

Refactoring involves improving the existing codebase without changing its external behavior, while rewriting refers to rebuilding the code from scratch to address underlying issues.

When should I consider refactoring or rewriting legacy code?

You should consider refactoring when you want to improve the quality of the code without changing its functionality, and rewriting when the existing codebase is too outdated or cumbersome to work with.

What are the advantages of refactoring over rewriting legacy code?

Refactoring allows incremental improvements to the code, reduces technical debt, and preserves the existing system’s business logic and knowledge, whereas a full rewrite involves higher risk and resource investment.

What are the benefits of rewriting legacy code compared to refactoring?

Rewriting legacy code provides an opportunity to utilize modern technologies and design patterns, eliminate technical debt, and create a more maintainable and scalable system compared to incremental refactoring.

How do I decide between refactoring and rewriting legacy code?

The decision depends on the extent of technical debt, the maintainability of the existing system, the available resources, and the long-term goals for the application’s architecture and functionality.

Can refactoring legacy code address technical debt effectively?

Yes, refactoring helps in addressing technical debt by gradually improving the codebase, enhancing its maintainability, and reducing the risk of introducing new issues compared to a full rewrite.

What are the risks associated with refactoring legacy code?

Risks of refactoring include the potential introduction of new bugs, increased time and effort, and the need for a thorough understanding of the existing system to avoid unintended consequences during the process.

Is rewriting legacy code a time-consuming process?

Yes, rewriting the codebase from scratch requires significant time and resources. This includes re-evaluating requirements, redesigning the architecture, and re-implementing the system, which can be a lengthy process.

How can a successful code rewrite impact the overall software system?

A successful rewrite can result in improved code quality, enhanced performance, reduced technical debt, and the ability to adapt to changing requirements, ultimately leading to a more sustainable and efficient software system.