Code Refactoring: best practices, techniques & tools

DevOps Trends & Technology
code refactoring

The code refactoring process involves restructuring existing code without changing its external behavior. It’s like renovating a house to enhance its functionality and aesthetics while keeping the foundation intact. 

Code refactoring doesn’t fix bugs or add new features; it’s about improving the overall design, readability, and performance of the code. In this article, we’ll explore the importance of refactoring and provide some key strategies for streamlining your codebase.

Why do you need code refactoring?

Refactoring is an ongoing process that should be performed regularly, ideally as part of the development workflow. It is typically carried out iteratively, focusing on small, incremental changes to minimize the risk of introducing errors or regressions. Through refactoring, developers continuously improve the codebase, ensuring its long-term sustainability and adaptability to changing requirements.

Main benefits of refactoring

The code refactoring process is a never-ending story. But the key to success is regularity and systematic work. Your team has to spend some time on it, but we assure you that this small investment of time will return to you more flexible solutions, repay technical debt, and finally – more costless mistakes and amendments.

  1. Improve Code Readability: Readable code is easier to understand and maintain, leading to better collaboration among developers and reduced time spent on deciphering code.
  2. Enhance Code Maintainability: By removing redundant code and reducing complexity, refactoring enhances code maintainability and simplifies modification.
  3. Enhanced extensibility: Refactoring helps to isolate code components, making it easier to add or change functionality without affecting other parts of the system.
  4. Performance Optimization: Refactoring can lead to performance improvements by optimizing algorithms, and data structures, or eliminating unnecessary computations. 
  5. Increase Code Reusability: Refactoring promotes code reusability by extracting common functionality into reusable methods or classes.
  6. Adapt to Changing Requirements: Refactoring enables the codebase to be more flexible and adaptable to evolving requirements. It helps in removing unnecessary dependencies, reducing coupling between components, and applying design patterns to facilitate future modifications or feature additions.
  7. Facilitate Code Reviews and Onboarding: Well-refactored code is easier to review, understand, and onboard new developers.

Code refactoring and technical debt

Technical debt accumulates when shortcuts or suboptimal design choices are made during development. Refactoring helps in paying off this debt by systematically improving the codebase, reducing complexity, and addressing code quality issues. By refactoring regularly, developers prevent technical debt from accumulating and ensure the long-term sustainability of the codebase.

Basics of refactoring

The code refactoring process involves applying various techniques to improve the structure and design of your code. Here are some of the main techniques commonly used in code refactoring:

  1. Extract Method: Identify sections of code that can be grouped and extracted into separate methods. This technique improves code readability, eliminates duplication, and promotes code reuse.
  2. Rename: Use meaningful and descriptive names for variables, functions, and classes. Renaming entities clarify their purpose, improves code understanding, and makes maintenance easier.
  3. Remove Duplication: Identify duplicate code blocks and extract them into reusable functions or methods. Duplicated code increases the risk of inconsistencies and makes future modifications cumbersome. By eliminating duplication, you enhance maintainability and reduce the chances of introducing bugs.
  4. Extract Class: When a class becomes too large or handles too many responsibilities, it’s advisable to extract a subset of its functionality into a new class. This technique improves code organization, promotes encapsulation, and makes classes more focused and cohesive.
  5. Inline Method: If a method is no longer necessary or adds unnecessary complexity, you can inline it by replacing all calls to the method with its actual implementation. This technique helps simplify code and remove unnecessary abstractions.
  6. Replace Conditional with Polymorphism: When you have complex conditional statements, consider using polymorphism to replace them with a more flexible and extensible design. This technique improves code readability, eliminates duplication, and makes it easier to add new variations or behaviors in the future.
  7. Split Large Classes: If a class becomes excessively large and handles multiple responsibilities, splitting it into smaller classes with distinct responsibilities can improve code organization and maintainability. Each class can then focus on a specific aspect of the overall functionality, promoting the Single Responsibility Principle.
  8. Introduce Design Patterns: Utilize well-known design patterns, such as the Factory Method, Observer, or Strategy patterns, to improve code structure and flexibility. Design patterns provide proven solutions to common problems and enhance code maintainability and extensibility.
  9. Remove Dead Code: Identify and remove any unused variables, functions, or classes from your codebase. Dead code clutters the codebase and adds unnecessary complexity, making it harder to understand and maintain.
  10. Simplify Complex Expressions: If you encounter complex or convoluted expressions, break them down into simpler, more readable components. This technique improves code clarity and reduces the likelihood of introducing logic errors.

Remember, the choice of technique depends on the specific context and goals of your refactoring efforts. It’s crucial to have a solid understanding of your codebase and its requirements to apply the most appropriate refactoring techniques effectively.

Code refactoring best techniques 

If you are wondering which is the best moment of the project to refactor the code it is worth keeping in mind two key stages: 

– before implementing new functionality into existing code, 

– after the product has been rolled out to the market when the software development team can calmly focus on updates and patches. 
Depending on the project and the capabilities of your team, you should choose a refactoring technique that will allow you to achieve your goals. You can use one of the most popular techniques: 

The Red-Green Refactor

This is a common approach used in Test-Driven Development (TDD). It is a cycle that helps guide the development process by emphasizing test coverage and code quality. The cycle consists of three steps: red, green, and refactoring.

The Red-Green Code Refactoring

Red: In the “Red” phase, you write a failing test case. This test case typically represents a new feature or functionality that you want to implement or a bug that needs fixing. Initially, the test fails because the corresponding code is not yet implemented or contains a defect.

Green: In the “Green” phase, you write the minimum amount of code required to make the failing test pass. The focus is on making the test case succeed without concerning code quality or optimization. This step ensures that the code meets the expected behavior defined by the test.

Refactor: In the “Refactor” phase, you improve the code’s structure, readability, and performance without changing its external behavior. This includes applying code refactoring techniques, removing duplication, improving naming conventions, and optimizing the design. The goal is to enhance the code’s maintainability and quality while keeping the tests passing.

Refactoring by Abstraction

In turn, this technique is used to reorganize code within an inheritance hierarchy by moving methods or attributes between classes. 

Code Refactoring by Abstraction

The most popular approach is the Pull-Up/Push-Down method consists of identifying common behavior or attributes in related classes and deciding whether to move them up in the inheritance hierarchy (Pull-Up) or push them down to more specific subclasses (Push-Down). This technique helps improve code structure, eliminate duplication, and enhance the clarity of class responsibilities.

Composing Method

Refactoring code using the “Composing Method” technique involves breaking down large, complex methods into smaller, more manageable pieces. The two primary approaches to refactoring code using this technique are Extraction and Inline. Let’s explore both:

Extract method refactoring refers to the process of dividing code into smaller segments in an attempt to identify and separate individual parts. These fragmented sections are then moved to independent methods and replaced with method calls to the newly created methods. In addition to methods, extraction may also involve separating code into classes, interfaces, and local variables.

Inline is a technique used to streamline code by reducing the presence of unnecessary methods. It involves identifying all method calls and replacing them with the actual code contained within the method. Once this is done, the method itself can be safely removed from the codebase. This process simplifies the code and eliminates the need for an extraneous method.

Simplifying Methods

Simplifying methods in code refactoring involves making the code within methods easier to understand, clearer, and more concise. This can be achieved by removing duplicate code, reducing method length, extracting complex logic into separate methods, using descriptive naming, eliminating unnecessary code, utilizing standard library functions, and following coding conventions. Simplifying methods improve code readability, maintainability, and debugging, without changing the external behavior of the code.

Moving Features Between Objects

This approach entails creating new classes and transferring functionality between existing and new classes. When a class becomes overloaded with too much responsibility, it becomes necessary to redistribute some of its code to another class. Conversely, if a class lacks significant functionality, its features can be moved to another class, ultimately leading to the removal of the redundant class.

Preparatory refactoring

The preparatory refactoring process refers to the practice of making code changes in preparation for implementing new features or addressing upcoming requirements. It involves proactively restructuring the codebase to improve its maintainability, extensibility, and readability before introducing new functionality. It is important to maintain a working codebase throughout the refactoring process and regularly run tests to ensure that the behavior of the code remains intact.

Preparatory Refactoring – code refactoring

The main objective of preparatory refactoring is to set a solid foundation for future development by eliminating technical debt, reducing code complexity, and enhancing code organization. By performing refactoring tasks in advance, developers can avoid potential pitfalls and make it easier to implement changes or add new features in the future.

Code refactoring tools 

Code refactoring tools are software applications or plugins that assist developers in automatically performing code refactoring tasks. These tools can analyze code, identify areas for improvement, and apply refactorings based on predefined rules or user-defined configurations. Here are some popular code refactoring tools:

IntelliJ IDEA: A popular integrated development environment (IDE) that provides powerful refactoring capabilities for various programming languages, including Java, Kotlin, and JavaScript. It offers automated refactorings, such as extracting methods, renaming variables, and introducing variables.

Eclipse: Another widely used IDE that supports refactoring for languages like Java, C/C++, and Python. It offers automated refactorings like extract method, inline method, and rename.

Visual Studio: Microsoft’s integrated development environment that includes built-in refactoring features for languages such as C#, Visual Basic, and C++. It provides refactorings like extract method, renames, and extract interface.

ReSharper: A popular refactoring tool for Microsoft Visual Studio that supports C# and VB.NET. It offers a wide range of automated refactorings, code inspections, and suggestions for improving code quality.

SonarQube: A continuous code quality tool that can also assist in identifying and addressing code smells and maintainability issues. It offers static code analysis and provides recommendations for refactoring.

CodeClimate: A cloud-based platform that provides automated code analysis and helps identify maintainability issues in code. It offers insights into potential refactoring opportunities and provides suggestions for improvement.

JUnit: A testing framework that can be used for test-driven refactoring. By writing unit tests before making changes, developers can refactor code with confidence, knowing that the tests will ensure the expected behavior is maintained.

These are just a few examples of code refactoring tools available in the market. The choice of tool depends on the programming language, development environment, and specific refactoring needs. It’s important to evaluate the features, compatibility, and community support of each tool before incorporating them into your development workflow.

How to perform code refactoring?

When it comes to code refactoring, there are several best practices to follow to ensure effective and successful results. Here are some key best practices for code refactoring:

Understand the Code: Gain a comprehensive understanding of the existing codebase before starting the refactoring process. Analyze the code, its functionality, and any potential issues or areas for improvement.

Have Clear Goals: Define clear goals and objectives for the refactoring process. Identify what aspects of the code need improvement, such as enhancing readability, improving performance, or reducing complexity.

Test Coverage: Ensure that the code being refactored has a comprehensive test suite in place. This helps validate that the behavior of the code remains consistent after refactoring. Run tests regularly during the refactoring process to catch any introduced bugs or regressions.

Make Small Changes: Refactor the code in small, incremental steps rather than attempting large-scale changes. This makes it easier to track the impact of each modification and allows for easier debugging if issues arise.

Preserve Functionality: Maintain the external behavior of the code during refactoring. Refactoring should not introduce changes in the functionality of the code unless it is part of the intended improvement.

Keep Code Review in Mind: Involve other developers or team members in the refactoring process. Conduct code reviews to get feedback and ensure that the changes align with coding standards and best practices.

Refactor for Readability: Prioritize code readability and maintainability. Write clean, self-explanatory code that is easy to understand for future developers who may work on the codebase.

Eliminate Code Duplication: Identify and remove duplicated code by extracting it into reusable functions or classes. Duplication increases maintenance efforts and the risk of inconsistencies.

Follow Design Principles: Apply software design principles such as SOLID (Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion) to improve the overall architecture and design of the codebase.

Document Changes: Document the refactoring changes made to the codebase, including the reasons behind the modifications, any trade-offs, and potential impact on performance or behavior.

Refactor Regularly: Make refactoring an ongoing process. Regularly review and refactor code to maintain its quality and prevent the accumulation of technical debt.

Use Version Control: Utilize version control systems to track and manage code changes during the refactoring process. This allows you to revert to previous versions if necessary and provides a safety net.

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