Refactoring: what is it and why is it important?

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What is refactoring?

Refactoring is a common practice in the field of software development, which involves restructuring the source code of a program without changing its external behavior. The primary goal of refactoring is to improve the quality of the code, making it more readable, maintainable, efficient, and often reducing complexity.

Refactoring is an ongoing practice that can be performed at any stage of the software development lifecycle. It is carried out step by step, incrementally, ensuring that the code remains functional after each change. The use of development and automated testing tools is often essential for safe and error-free refactoring.

In short, refactoring aims to improve the quality of the code, making it more easily understandable, maintainable, and efficient, thus contributing to reducing the long-term development and maintenance costs.


What is code refactoring used for?

Refactoring is often performed to achieve the following objectives:

  1. Improve code readability: Make the code clearer and more understandable to programmers so that it is easier to read, interpret, and maintain. This may involve renaming variables, splitting complex code into smaller functions, or removing duplicated code.
  2. Enhance maintainability: Facilitate adding new features or fixing bugs, reducing the likelihood of introducing new errors when making changes to the code.
  3. Increase efficiency: Identify and optimize parts of the code that may slow down the program, improving performance without changing external behavior.
  4. Reduce complexity: Simplify parts of the code that are overly complex or cumbersome. This can make the code easier to manage and less error-prone.
  5. Improve architecture: Modify the code’s structure to better align with design principles and best practices, such as applying design patterns or eliminating poor architectural practices.

When to plan for code refactoring

Code refactoring should be strategically and continuously planned and integrated into the software development process. It should not be viewed as an isolated activity or a one-time event. Here is when it is appropriate to plan and conduct refactoring:

  1. During the design process: Include refactoring in the software design phase. Before writing the code, plan how it will be organized and how complex parts will be handled.
  2. During development: During development, recognize that requirements may change, and new opportunities for refactoring may emerge. Maintain a readiness for refactoring and do not hesitate to improve the code when necessary.
  3. After completing a feature: After completing a feature or a significant portion of the software, it is a good practice to review the written code. If you find duplicated, complex, or unclear code, it is the ideal time for refactoring.
  4. When identifying bugs or performance issues: If you encounter bugs or performance issues in the software, refactoring may be necessary to efficiently address them. For example, if a bug is caused by a hard-to-understand code section, you can refactor that part to make debugging easier.
  5. Before expanding the software: Before adding new features or extending the software, review and improve the existing code. Quality existing code makes adding new features easier.
  6. In response to changing requirements: If project requirements change, refactoring may be necessary to adapt the software to these changes efficiently.
  7. Continuously during the development cycle: Refactoring should not be seen as a periodic activity but rather as an ongoing process. It should be an integral part of daily development.
  8. Regular maintenance: Do not wait until the code becomes messy before refactoring it. Schedule regular reviews and improvements to ensure that the code remains clean and maintainable.
  9. During technical improvement moments: If you want to adopt new technologies or improve code quality in general, refactoring can be a part of this effort.

The key is to have a balanced approach to refactoring. Excessive ongoing refactoring can excessively slow down development, while complete rejection of refactoring can lead to low-quality code that is difficult to maintain. Therefore, finding the right balance based on project needs and code conditions is important.

Refactoring techniques and methods

There are numerous code refactoring techniques and methods that programmers can use to improve the quality of the source code without changing its external behavior. Here are some of the most common refactoring techniques:

  • Rename: Change the name of variables, functions, classes, or modules to make them more descriptive. This increases code readability.
  • Extract Method: Extract a block of code into a new function or method to make the code more readable and reduce duplication.
  • Extract Variable: Create a variable to store a complex or repeated expression, making the code clearer and easier to understand.
  • Move Method: Move a method from one class to another if the method is more relevant in a different context.
  • Move Field: Similar to moving a method, but it concerns the attribute of a class instead of the method.
  • Remove Parameters: Reduce the number of parameters of a function, if possible, to simplify the function’s invocation.
  • Simplify Conditional Expressions: Simplify complex conditional expressions, such as nested if-else statements, to make them more readable.
  • Combine Methods: Combine two or more similar methods into one, reducing code complexity.
  • Remove Dead Code: Eliminate code that is never used or reached anywhere in the program.
  • Group Variables: Group related variables into data structures, such as objects or arrays, to improve code organization.
  • Extract Interface: Create an interface to abstract the functionalities of a class so that you can use the interface in various contexts.
  • Split Class: Split a class into two or more smaller classes to improve cohesion and clarity.
  • Replace Duplicate Code: Identify and remove duplicated code to avoid bugs and simplify maintenance.
  • Replace Magic Strings/Numbers: Replace literal constants (e.g., magic strings or numbers) with named constants to make them more explicit.
  • Replace Hierarchy with Field: Replace a class hierarchy with a field or attribute to simplify the structure.
  • Extract Superclass: Create a common base class to share code between related classes.
  • Long Method Refactoring: Divide long methods into smaller methods to improve code readability and maintainability.

These are just some of the many refactoring techniques available. It’s important to note that refactoring should be performed cautiously and supported by automated tests to ensure that changes do not introduce new bugs. Additionally, it’s a recommended practice to include refactoring as part of the continuous development process to keep the code in a high-quality state.


Code refactoring tips

Code refactoring is an essential activity to maintain high-quality source code and improve its readability and maintainability. Here are some tips and best practices for conducting effective refactoring:

  • Automated tests: Before starting any refactoring, make sure you have a robust set of automated tests. Tests will help you verify that the changes do not introduce new bugs. Run tests before and after refactoring to confirm that the software’s behavior remains unchanged.
  • Planning: Plan your refactoring carefully. Consider which parts of the code require improvements and how you can break them down into manageable steps. Define clear goals for the refactoring.
  • Small steps: Perform refactoring in small incremental steps. Changing one small part at a time makes it easier to manage the changes and maintain control over the process.
  • Understanding the code: Before you start refactoring a code section, make sure you fully understand how it works. A good understanding of existing code is essential to avoid errors and unintended behavior.
  • Avoid excessive comments: If you find it necessary to extensively comment the code, it might be a sign that the code is unclear. Instead of commenting, try to make the code more descriptive and self-explanatory through refactoring.
  • Keep the code open: During refactoring, keep the code open and accessible to the entire team. Collaboration and feedback from other team members can be very helpful.
  • Monitor code quality metrics: Use code quality tools and metrics, such as cyclomatic complexity, code coverage, and static analysis, to assess the effectiveness of refactoring.
  • Version control: Ensure you use a version control system like Git. This allows you to track changes, roll back if necessary, and collaborate with others during refactoring.
  • Maintain updated documentation: Update code documentation, such as in-source code comments or external documentation, to reflect the changes made during refactoring.
  • Adhere to SOLID principles: The SOLID principles (Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, Dependency Inversion) are important guidelines for designing high-quality code. During refactoring, try to apply these principles whenever possible.
  • Incremental improvements: Do not attempt to fix all problems in a single refactoring session. Make incremental and regular improvements over time.
  • Feedback and sharing: Share your refactoring work with your team and seek feedback. Other team members may provide valuable insights.
  • Measure impact: After completing refactoring, evaluate whether the intended improvements have been achieved. Monitor code performance, readability, and maintainability to see if they have improved.

Refactoring is an ongoing practice and should be incorporated into the development cycle. Do not wait until the code becomes too messy to start refactoring. Keeping the code clean and of high quality makes long-term maintenance easier and improves development efficiency.

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