Code Refactoring Explained

If there's one fact every developer has to deal with, it's that there's no perfect code. Just code that gets the work done. However, there's still the need for the occasional code cleanup or modification, which is a simplified explanation for code refactoring. 

This article explains code refactoring, including its benefits, time-tested techniques, tools, and best practices for nailing it.

What is refactoring?

Refactoring is modifying a code's behavior or internal structure without impacting its external structure. The goal of refactoring is not functional, i.e., fixing performance issues. Instead, it's visual as you're touching up the code design to enable code readability maintainability and prevent the accumulation of technical debt.

If you struggle to understand refactoring, think of the infamous first draft. It’s the first version of every piece that writers must produce and edit before the final version gets to you, the reader. That's how refactoring works, too. But in this case, "the first draft," i.e., the first version of the code, is allowed to go live. Such codes may function and give the end user what they need; this could be a functional website or a new product feature, but the code quality still needs improvement. 

Rather than allowing perfectionism to keep you or your engineering team from shipping code to production, code refactoring steps in after the code goes live to keep business moving. 

During refactoring, the changes are small enough to improve the code's design without making it unrecognizable or destroying the code repository. Examples of a code refactor are:

• Removing dead code
• Standardizing code formatting
• Changing a local variable name to make the code less confusing
• Renaming poorly named variables to make them more descriptive
• Breaking up long lines of code that perform multiple functions makes the code easier to maintain. 

When to refactor code

As helpful as refactoring is, it's not a task to be done at will. This is why timing matters, and from years of practice, software engineers and developers have realized that these are the best times to refactor code.

• During regular maintenance as part of your team's routine maintenance.
• Before adding new features to prepare the environment to accept the changes and prevent extra technical debt.
• During code and peer reviews. Your team will benefit from the flow of ideas from their peers while figuring out areas to refactor and the best ways to manage code.

Benefits of code refactoring

The following are the benefits of refactoring to an organization:

Ensures code functionality and maintenance

Refactoring reduces the buildup of technical debt, which refers to "future work to correct sub-optimal code.” Sometimes, tight deadlines push developers to opt for speed during code production instead of cleanliness. Other times, it’s multiple developers contributing to a code base and filling it with redundant elements. With refactoring, you get to rectify these issues before they escalate and affect the performance of your developers and engineers.

Saves time and energy

A modified codebase with smaller technical debt means your developers will have fewer reasons to keep tweaking the code in the future. Plus, it also saves money that would be spent solving data loss issues, system crashes, and lower deployment frequency, courtesy of poor code.

Identifies and fixes bugs

Beyond solving for redundancy, bugs are a prevalent issue that affects code performance. Hence, revisiting one's code and modifying it allows you to pick out bugs you may have missed areas due to work pressure or recently introduced ones. 

Contributes to developer education

The standard practice when refactoring is to do it in collaboration. You'll need to get approval, collaborate with other team members, and document each improvement and unit test (a part of overall software testing) as they take place. This setup—where the above practices are implemented—leads to knowledgeable employees and creates a resource base on which future employees can fall back.

Code refactoring techniques

There are several refactoring techniques your code can benefit from, but the following are the most common ones you should know:

Red-green refactor

This technique refers to test-driven development, a software development practice that requires the writing of tests before the actual code. 

Red-green refactoring is a three-step process involving: 

• Red: writing a test programmed to fail because it lacks the functionality needed to make the test a success. The red stage ensures the test can detect when the correct code has been deployed. 
• Green: This is where coding happens. The catch here is you write just enough code to pass the test you scripted in the first step. The green stage means your code is good to go. The code is fit to create a minimum viable product or just get production going. But the code meets the bare minimum requirement, which means it requires extra work for better quality. 
• Refactor: the stage for code cleanup. Here, you remove what's unnecessary, improve on specific areas, and keep iterating as much as possible. While doing it, you ensure the updated code still passes the quality assurance test and retains its functionality. 

Refactoring by abstraction

Developers use this technique to reduce duplication within large sets of code. As a programming rule of thumb states, “You are allowed to copy and paste the code once, but when the same code is replicated three times, it should be extracted into a new procedure." To do this, you categorize the code based on their shared attributes and either group them to reduce the lines of code or move them to another hierarchy within the code. 

This technique is common amongst Java programmers and involves two methods, namely:

• Pull-up method: it pulls or extracts code and moves it into a hierarchy known as the superclass.
• Push-down method: it pushes down code parts from a superclass into a subclass. 

Composing method

This technique corrects the composition of the codebase by dividing methods into small blocks to enhance code readability and reduce complexity. 

It's done in two ways: using the extraction method and the inline method.

• Extraction method. In the extract method, you improve code by breaking down a method into smaller blocks with unique functions. Let's say you have a method performing multiple functions simultaneously. You can extract a fragment of the code, create a standalone method for that fragment with a singular task, and link the original method to the new one. This way, the old and new methods function without disrupting the codebase. 
• Inline method. The inline method reorganizes and shortens a codebase by eliminating unnecessary methods or calls to methods that make the code harder to understand or longer. It's a straight-to-the-point approach that takes out the method itself, leaving only the content of the method for a cleaner code.  

Simplifying method

This technique simplifies code and makes it easier to understand, especially for aging code. There are two ways to go about it.

• Simplify the code's logic by modifying its original conditional statements. 
• Simplify method calls through modifying the relationship between classes by adding or removing parameters, preserving the whole object, or renaming the methods. 

There are more ways to apply this technique, but it's left to the developer to apply discretion based on the code's structure and issues. 

Best practices for code refactoring

The following practices will help your team give your best to an existing codebase when refactoring:

Analyse the code

First, understand why the code exists and if there's any history of refactoring that has been documented before jumping in.  You should start from the root to know why the code is that way and the process by which the code came to be. Again, refactoring may be a small part of the software development cycle, but it can also destroy a system if it is done without care. Always remember Chesterton's Fence: Before making changes you must first understand the rationale behind previous decisions.

Be ready to justify the decision to refactor to management

This is in case there's a complex issue you need to handle while refactoring that eats into engineering's budget,  things go haywire along the line, or management doesn't see the need for refactoring at a point in time. Prepare a "what's at stake" analysis for management, explaining that it will be a long-term investment. Show how the benefits of a well-designed code, thanks to refactoring, will help the company in the long run. 

Refactor as a team, it's not a one-man show

Never take on refactoring alone, especially if you're part of a team. Brainstorming for ideas and shared responsibility in handling risks are some of the benefits you'll enjoy when you refactor within a group.

Test at every stage

One of the things every programmer should know is the importance of unit testing, and this applies to refactoring, too. Always conduct unit tests before refactoring, and test the minor changes from refactoring.

Work with refactoring tools

Some software applications can automate and handle some aspects of the refactoring process, which you can use. These tools work based on the programming language and the technique in use. Examples of these tools are:

• IntelliJ idea
• Sonarlint
• Visual Studio
• Resharper
• Eclipse IDE

Ensure code health through refactoring

Routine refactoring helps keep your code quality high and gives your developers less work to do when working with existing code. If you stick to the best practices and keep up with coding standards, it will be a low-risk venture for your company.