Refactoring is a disciplined technique for restructuring an existing body of code, altering its internal structure without changing its external behavior. Its heart lies in a series of small behavior-preserving transformations. Even a small change can have a profound impact on the system’s architecture, thereby enhancing its readability and maintainability, which are crucial parameters for the Agile methodology.
Refactoring is one of the core tenets for a Certified Scrum Developer (A-CSD). This article aims to demonstrate a systematic approach towards refactoring a system for better maintainability.
To keep it simple and coherent, we’ll focus on the commonly used “Extract Method” refactoring approach.
The Extract Method Refactoring Technique
The Extract Method is one of the simplest and most impactful methods to refactor the code. In this approach, you take a code segment that can be grouped together, move it to a separate new method, and replace the old code with a call to the method.
This technique becomes helpful when a method runs too long, or the code within it performs operations that would be better suitable for independent procedures. This process reduces the code’s complexity and improves reusability and maintainability.
Let’s understand this with the help of an example,
Before Refactoring:
def print_bill(debt):
print(”)
print(‘ Customer ‘)
print(”)
print(‘Name:’, debt.customer)
print(‘Amount:’, debt.amount)
In the above code, we are printing a bill. The code for printing the header is mixed with the logic for printing the customer details. This code can be refactored to separate the concern of printing the header from printing the customer details.
After Refactoring:
def print_header():
print(”)
print(‘ Customer ‘)
print(”)
def print_bill(debt):
print_header()
print(‘Name:’, debt.customer)
print(‘Amount:’, debt.amount)
In the refactored code, the method `print_header()` is extracted to separate the code that prints the header. This same method can now be reused to print the header for other sections of the bill as well.
Why Refactor for Maintainability?
1. Improved readability
Programmers are often not the authors of the code they maintain. Well-factored code is easier to read and comprehend, which accelerates the learning process for a newcomer to the system. When methods and classes are small and well-named, they act as a form of documentation.
2. Easier bug detection
Well-partitioned, modular code with clear responsibilities can simplify the bug detection process as the developer has fewer places to look for possible malfunctioning.
3. Simplification of changes
Modular code allows developers to make changes in one place without affecting others. Extracted methods, which have a single responsibility, can absorb changes for that responsibility without requiring modifications throughout the code base.
However, like every technique, refactoring should be done sensibly. It could introduce bugs if not done properly.
In conclusion, refactoring can go a long way toward making your code more readable and maintainable, both of which are critical elements for agile development—a key skill for an aspirant preparing for the Advanced Certified Scrum Developer (A-CSD) exam.
Practice Test
True or False: Refactoring is the process of changing a software system in such a way that it does not alter the external behavior of the code yet improves its internal structure.
• True
• False
Answer: True
Explanation: This is the standard definition of refactoring in software development and an essential task to maintain software system.
In the context of refactoring, what does the term ‘code smell’ refer to?
• A) An error in the code
• B) Hints that something might be wrong in the code, despite it functioning properly
• C) A virus in the code
• D) An unoptimized part of the code
Answer: B) Hints that something might be wrong in the code, despite it functioning properly
Explanation: ‘Code smells’ are just symptoms of deeper problems in the code that should be addressed with refactoring.
True or False: Refactoring always involve changing the outward functionality of a system.
• True
• False
Answer: False
Explanation: The main goal of refactoring is to improve the internal structure of the code without affecting its external behavior or functionality.
Which of the following is NOT a reason to refactor a system?
• A) To make the code easier to understand
• B) To improve performance
• C) To add new features
• D) To prevent future bugs
Answer: C) To add new features
Explanation: While refactoring can make adding new features easier, it shouldn’t be the primary reason to refactor a system. Its main purpose is to improve the internal structure and maintainability of the code.
Continuous refactoring is a practice belonging to which of the following methodologies?
• A) Agile
• B) Waterfall
• C) PRINCE2
• D) None of the above
Answer: A) Agile
Explanation: Continuous refactoring is traditional in Agile development methodology to ensure the system remains flexible and easy to maintain.
True or False: The primary purpose of refactoring is to find bugs.
• True
• False
Answer: False
Explanation: While refactoring might inadvertently reveal bugs, its main purpose isn’t to find them, but to improve the system’s internal structure for enhanced maintainability.
Which of the following is an example of a refactoring technique?
• A) Code commenting
• B) Code compiling
• C) Extract method
• D) Code executing
Answer: C) Extract method
Explanation: Extract method is a technique that involves turning a segment of code into a new method or function, thereby improving readability and reusability.
Who should be involved in the refactoring process?
• A) Developers
• B) System administrators
• C) Product owners
• D) All of the above
Answer: A) Developers
Explanation: Refactoring is primarily a developers’ task, as it entails improving the internal structure of the code.
True or False: Refactoring should always be included in the original estimation of the software development project.
• True
• False
Answer: True
Explanation: Refactoring is a critical part of the software improvement process and should be accounted for in the original project planning and estimation.
What is a safe time to refactor a system for maintainability?
• A) Before introducing a new feature
• B) While fixing a bug
• C) When the code passes all tests
• D) All of the above
Answer: D) All of the above
Explanation: Refactoring can, and should, be done at any point in the software development cycle, as long as it’s done safely and carefully.
True or False: Automated tests are not necessary when refactoring.
• True
• False
Answer: False
Explanation: Automated tests are critical during refactoring as they ensure the modifications in the code have not altered the software’s behavior.
How often should refactoring be done?
• A) Only when a system is about to break down
• B) At the end of each sprint
• C) As soon as ‘code smells’ are detected
• D) Only when there is spare time during a project
Answer: C) As soon as ‘code smells’ are detected
Explanation: To maintain a clean codebase, refactoring should be done as soon as any signs of code degradation are noticed.
Interview Questions
What is the main reason to refactor a system?
The main reason to refactor a system is to improve its internal structure without altering its external behavior, making it easier to maintain and extend in the long run.
What is ‘code smell’ in the context of software development?
‘Code smell’ refers to any symptom in the source code of a program that may indicate a deeper problem, often suggesting that code refactoring may be needed.
Can we refactor code without tests?
It’s possible, but not recommended. Tests provide a safety net, ensuring that refactoring doesn’t break any functionality.
What do we need to assure before applying refactoring to a system?
We need to assure that there are trustworthy and well-covered tests before applying refactoring.
Name at least one type of code refactoring technique.
Composing Methods is a type of refactoring technique where long methods are divided into smaller, more manageable parts.
What’s the main goal of refactoring?
Refactoring aims to improve the design, structure, and/or implementation of the software while preserving its functionality.
Can Agile and Scrum methods include refactoring procedures?
Yes, Agile and Scrum methods can and often do include refactoring as part of their approaches to keep the codebase clean and maintainable.
What is a simple definition of ‘Refactoring’?
Refactoring is the process of restructuring existing computer code without changing its external behavior.
Can you name a tool usually used for code refactoring?
Integrated Development Environments (IDEs) like IntelliJ IDEA and Eclipse often come with built-in refactoring tools.
How can implementing a clean, understandable codebase aid in system maintainability?
Clean, understandable codebases are easier to manage, extend, and debug, hence improving maintainability.
What is the role of the SOLID Principles in Refactoring?
SOLID principles are guidelines that can be used during refactoring to ensure that a system is easy to maintain, understand, and extend.
Is encapsulating field a valid approach to refactor a system for maintainability?
Yes, encapsulating fields is a common refactoring technique whereby access to certain class attributes is controlled by getter and setter methods, enhancing encapsulation and maintainability.
Is it necessary to completely stop development to undertake Refactoring?
No, refactoring is typically integrated into the development process and can be done iteratively alongside development work.
What is the danger of a “Big Bang” refactoring approach?
The ‘Big Bang’ refactoring approach can be risky due to its size and scope. It can introduce new bugs, irritate stakeholders with its time-consuming nature, and threaten the stability of the existing system.
How does Refactoring aid in Preventive Maintenance?
Refactoring can help detect and correct latent defects before they become problems. By keeping the code clean, potential problems can be easily identified and corrected, thereby aiding in preventive maintenance.
extutorials.com