Code Refactoring: 6 Techniques and 5 Critical Best Practices

What Is Code Refactoring? 

Code refactoring is the process of improving the internal structure, readability, and maintainability of a software codebase without altering its external behavior or functionality. This practice aims to enhance code quality and reduce technical debt by reorganizing, simplifying, or optimizing the code, making it more efficient, modular, and easier to understand for developers.

When Should You Consider Software Refactoring? 

You should consider software refactoring in the following situations:

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• Low readability and maintainability: If the code is difficult to understand or modify due to poor organization, inconsistent naming conventions, or lack of comments, refactoring can help improve its clarity and ease of maintenance.
• Updating to newer technologies or libraries: When migrating to a new technology stack or upgrading libraries, refactoring can help ensure compatibility and smooth integration.
• Improving performance: When you identify areas of the code with inefficient algorithms or data structures, refactoring can help optimize the code and enhance its performance.
• Code smells: If you identify recurring patterns or issues in the code that indicate poor design or implementation, such as duplicated code, large classes, long methods, or excessive use of global variables, refactoring should be considered.
• Enhancing modularity and reusability: If the code has tightly coupled components or lacks modular design, refactoring can help break it into smaller, more manageable pieces with well-defined interfaces, promoting reusability and easier testing.
• Preparing for new features or changes: Before implementing new functionality or making significant changes to the existing codebase, refactoring can help create a cleaner, more adaptable foundation.
• Simplifying the codebase: If the code contains redundant or overly complex logic, refactoring can help streamline the code and make it easier to manage.

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It's essential to approach refactoring carefully, as it can introduce new bugs or issues if not done correctly. Make sure to have proper test coverage and version control in place before starting the refactoring process.

6 Code Refactoring Techniques You Should Know

1. Red-Green-Refactor

This technique is an integral part of test-driven development (TDD), a software development methodology that emphasizes writing tests before writing the actual code. The process consists of three main steps:

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• Red: Write a failing test that exposes the issue or required functionality. The goal is to create a test that will fail because the desired functionality has not been implemented yet. This step ensures that the test is valid and can detect the absence of the intended feature.
• Green: Write the minimum code necessary to pass the test. In this step, you focus on implementing the functionality needed to make the test pass, without worrying about the quality or maintainability of the code. The primary goal is to make the test pass as quickly as possible.
• Refactor: Improve the code while keeping the test green (i.e., without breaking the functionality). Once the test passes, you can refactor the code to make it cleaner, more efficient, and maintainable. The test serves as a safety net during the refactoring process, ensuring that the external behavior remains unchanged.

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This cycle of red-green-refactor is repeated for each new feature or bug fix, promoting a development process where the code is continuously tested and refactored, resulting in higher-quality and more reliable software.

2. Refactoring by Abstraction

Refactoring by abstraction is a technique where you identify common functionality shared by multiple classes or methods and extract it into a separate, abstract class or interface. This process helps reduce code duplication, promotes reusability, and makes it easier to manage and maintain the shared functionality.

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For example, consider two classes with similar methods that perform the same calculations. By extracting the shared logic into an abstract class or an interface, you can create a single implementation that both classes can inherit or implement. This abstraction reduces the amount of duplicated code and makes it easier to update or modify the shared functionality in the future.

3. Composing

This refactoring technique focuses on breaking down large classes or methods into smaller, more manageable components. The primary goal is to improve code readability, maintainability, and testability by making sure each component has a single responsibility. 

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This approach promotes a modular and organized codebase, making it easier to understand, modify, and extend in the future. Composing encourages a clean separation of concerns, which results in higher-quality and more reliable software.

4. Simplifying Methods

This refactoring technique aims to make methods more understandable and maintainable by reducing their complexity. It involves various approaches that simplify the code, such as reducing the number of method parameters, replacing complex conditional logic with simpler constructs, or breaking down long methods into smaller, focused methods.

5. Moving Features Between Objects

This technique focuses on reassigning responsibilities or methods between classes to improve cohesion (how closely a class's responsibilities are related) and reduce coupling (the degree to which one class depends on another). By redistributing code or functionality among classes, you create a more balanced and logical design that is easier to maintain and extend.

6. Preparatory Refactoring 

This approach is used when preparing the codebase for new features or significant changes. The objective is to create a cleaner, more adaptable foundation for future development by restructuring code, updating deprecated APIs or libraries, or simplifying complex logic. Preparatory refactoring helps ensure the codebase remains maintainable, testable, and scalable as new functionality is added.

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Learn more in our detailed guides to:

• Code refactoring examples (coming soon)
• Code refactoring techniques (coming soon)

5 Code Refactoring Best Practices 

1. Collaborate with Testers

Engaging the quality assurance (QA) team during the refactoring process ensures that the changes made do not introduce new bugs or negatively impact the software's functionality. The QA team can help validate that the refactored code behaves as expected, maintaining the software's quality and reliability.

2. Automate the Process 

Utilizing automated tools for code analysis, testing, and refactoring can help streamline the process and minimize the risk of introducing errors. Tools like static code analyzers, linters, and automated testing frameworks can help identify code smells, enforce coding standards, and ensure the refactored code meets the required quality criteria.

3. Refactor in Small Steps

Making small, incremental changes during the refactoring process reduces the likelihood of introducing bugs or breaking the software. By focusing on one improvement at a time, you can more easily identify and fix issues, making it easier to maintain a stable codebase throughout the refactoring process.

4. Troubleshoot and Debug Separately

Refactoring should be kept separate from bug fixing and troubleshooting. Mixing the two can lead to confusion and complicate the process of identifying the root causes of issues. Address known bugs before refactoring, and treat any new issues that arise during refactoring as separate tasks to maintain clarity and focus.

5. Prioritize Code Deduplication

One of the primary goals of refactoring is to eliminate duplicated code, as it can lead to inconsistencies, increase maintenance complexity, and make the codebase more error-prone. Focusing on identifying and extracting common functionality into reusable components, such as abstract classes, interfaces, or utility methods, can greatly improve the maintainability and readability of the code.