Code Readability: Writing code for humans

Emmanuel Otieno's photo
Emmanuel Otieno
·

4 min read

Code readability is one of the most crucial aspects of software development that often gets overlooked in favor of functionality and performance. While writing code that works is important, writing code that other developers (including your future self) can understand is equally vital. This article explores the principles, practices, and benefits of writing readable code.

Why code readability matters

Software developers spend far more time reading code than writing it. Studies suggest that developers spend about 58% of their time understanding code rather than writing new code. When code is difficult to read, it becomes:

  • More expensive to maintain

  • More likely to contain bugs

  • Harder to modify or enhance

  • More challenging for new team members to work with

Core principles of code readability

1. Clarity of Intent

Your code should clearly express its purpose without requiring extensive documentation. This means choosing meaningful names for variables, functions, and classes that accurately describe what they represent or do.

Bad:

def p(x):
    return x * x

Good:

def calculate_squar(number):
    return number * number

2. Consistent Formatting

Maintain consistent formatting throughout your codebase. This includes:

  • Consistent indentation

  • Proper spacing around operators

  • Consistent placement of brackets and braces

  • Following established style guides for your programming language

3. Logical Organization

Structure your code in a way that makes logical sense. Related functionality should be grouped together, and each component should have a single, well-defined responsibility. This often means:

  • Breaking large functions into smaller, focused ones

  • Organizing related classes and functions into modules

  • Maintaining a clear hierarchy of components

Best Practices for Writing Readable Code

Meaningful Names

Choose descriptive names that reveal intent. Variables, functions, and classes should be named to answer three questions:

  • Why does it exist?

  • What does it do?

  • How is it used?

Consider the following examples:

Bad:

d = 7  # Number of days
fn = "data.txt"  # Filename
lst = get_items()  # List of active users

Good:

days_until_expiration = 7
user_data_filename = "data.txt"
active_users = get_active_users()

Function Design

Functions should be:

  • Small and focused on a single task

  • Named using verbs that describe their action

  • Limited in their number of parameters

  • Documented when their purpose isn't immediately clear

Comments and Documentation

Use comments judiciously. Good code should be self-documenting, but comments are valuable for:

  • Explaining complex algorithms

  • Clarifying business rules

  • Documenting API usage

  • Warning about edge cases or limitations

Bad comments explain what the code does:

# Loop through each user
for user in users:
    # Check if user is active
    if user.is_active:
        # Send email to user
        send_email(user)

Good comments explain why:

# Send welcome emails only to active users to comply with GDPR requirements
for user in users:
    if user.is_active:
        send_welcome_email(user)

Tools and Techniques for Maintaining Readability

1. Code Formatters

Utilize automated code formatters like:

  • Prettier for JavaScript

  • Black for Python

  • gofmt for Go

These tools ensure consistent formatting across your entire codebase.

2. Static Analysis Tools

Employ linters and static analysis tools to identify potential readability issues:

  • ESLint for JavaScript

  • pylint for Python

  • ReSharper for C#

3. Code Reviews

Regular code reviews help maintain readability by:

  • Ensuring code meets team standards

  • Identifying unclear sections

  • Sharing knowledge among team members

  • Catching potential maintenance issues early

Conclusion

Code readability is not just about making code look pretty—it's about making code maintainable, scalable, and collaborative. By following these principles and practices, you can write code that not only works but is also a pleasure to work with. Remember, code is read far more often than it is written, so optimize for readability first.

The time invested in writing readable code pays dividends throughout the entire lifecycle of your software project. As the famous quote attributed to Martin Fowler goes: "Any fool can write code that a computer can understand. Good programmers write code that humans can understand."

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