The hidden dangers of over-commenting in code

When we think about writing clean and maintainable code, comments often come to mind as a helpful tool. Comments are traditionally seen as a way to explain complex logic or provide context to the code.

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However, there's another side to this story: comments can also be "code smells." In this post, we'll explore why relying too much on comments might be indicative of underlying problems in your code.

The role of comments in code across various programming languages

In programming, no matter what language you are using, comments play a very important role. Whether it's the // and /* ... */ syntax in languages like Java and C++, or the # character in Python, comments are designed to make code easier to understand. They can be invaluable for the explanation of complex logic, the provision of context, or the identification of areas for future improvement.

However, misusing or overusing comments can lead to confusion and maintenance problems. Excessive, outdated, or redundant comments can obscure rather than clarify. This is especially true in collaborative environments.

In addition, the use of comments to compensate for convoluted code is often an indication that the code itself requires refactoring for clarity. The key is to strike a balance: Use comments to clarify, not to hide code complexity, ensuring that the codebase remains clean and understandable to all developers.

When comments indicate problems

1. Over-reliance on comments

Problem: Relying too heavily on comments to clarify complex code sections.

// Check if the user is eligible for rewards and the rewards are not expired 
if ((user.getRewardPoints() > 100) && (user.getRewardExpiry().after(new Date()))) { 
// ... 
}

In this instance, the comment tries to explain a complex conditional statement. While it does provide some insight, it also suggests that the code itself might be too complicated.

Solution: Simplify the code logic.

if (user.isEligibleForRewards()) {
  // ...
}

Refactoring the condition into a method isEligibleForRewards makes the code more readable and self-explanatory, reducing the need for a comment.

2. Outdated or misleading comments

Problem: Comments that no longer align with the code, cause confusion.

// Calculate monthly salary
employee.setAnnualSalary(employee.getHourlyRate() * 40 * 4);

This comment is misleading if the calculation method has changed but the comment hasn't been updated.

Solution: Regular updates and clear code.

Frequent review of comments and updating them to reflect code changes is essential. Additionally, writing self-explanatory code can often eliminate the need for such comments.

3. Masking bad code

Problem: Using comments to justify or explain away poor coding practices.

// Complex calculation because of special cases
int result = a + b; // For now, just summing up

Here, the comment is used as an excuse for not addressing the complexity of the calculation.

Solution: Addressing the root issue.

Instead of leaving a vague comment, it's better to simplify or properly implement the complex calculation.

4. Commented-out code

Problem: Keeping large blocks of unused code as comments.

// Old implementation - kept for reference 
// int oldResult = a * b;

This practice clutters the codebase and can lead to confusion about what code is active and what is not.

Solution: Clean code and version control.

Remove such commented-out code. For historical reference, rely on version control systems like Git, which can track changes over time.

5. Redundant comments

Problem: Comments that are unnecessary as the code is self-explanatory.

i++; // Increment i by 1

Such comments add no value as the code line itself is clear.

Solution: Trust in the code's clarity.

Avoid adding comments for straightforward code lines. Trust the reader's ability to understand basic operations without additional explanation.

Alternatives to over-commenting

1. Refactoring for clarity

Writing code that is inherently clear and easy to understand is key to reducing the need to comment. This often involves breaking down complex methods into smaller, more manageable functions. Each function has a single responsibility.

For example, it's better to have several smaller methods with clear, descriptive names, rather than one large method that performs several tasks. This approach not only makes the code easier to read. It also makes it easier to maintain and test.

2. Using meaningful names

The names we choose for our variables, methods, and classes can greatly affect how easy it is to read and understand. Descriptive and meaningful naming conventions make it easier for someone else (or even yourself later) to understand what the code is trying to do without having to write additional comments.

For example, a method name such as calculateMonthlySalary() is a lot more informative than something more generic such as calculate().

3. Writing documentation

Inline comments can be helpful. However, they may not always be the best way to document complex logic. External documentation may be a more appropriate platform for explaining the broader architecture, complex algorithms, or system integrations, such as README files, wikis, or software documentation tools.

This keeps the high-level overview separate from the code. It also keeps the code clean.

4. Code reviews

A critical practice for ensuring code quality is to conduct regular code reviews. They provide an opportunity for other developers to check the code for clarity, efficiency, and adherence to best practices.

Through code reviews, you can identify instances where a comment is being used as a crutch for unclear code. You can also work together to improve the readability and maintainability of the code.

Conclusion

While comments are an integral part of coding, they should be used wisely and sparingly. Their overuse can often indicate deeper problems within the code, such as complexity or lack of clarity.

By adopting practices such as clear refactoring, meaningful naming, external documentation, and regular code reviews, we can greatly improve the readability and maintainability of our codebases.

This not only makes our code easier for others to understand but also creates a more efficient and streamlined development process.