8. Python Comments: Writing Readable Code

As a seasoned coder, I’ve learned that writing readable code isn’t just about the right syntax; it’s about making your code understandable for humans. That’s where Python comments come into play. They’re the secret sauce to maintaining your sanity and that of your fellow developers when revisiting code weeks, months, or even years later.

In this article, I’ll dive into the best practices for using comments in Python. Whether you’re a beginner looking to get it right from the start or an experienced programmer aiming to refine your style, understanding how to effectively comment your code is crucial. Stick with me, and you’ll see how comments can transform your code from a tangled web to a well-told story.

Why Are Python Comments Important?

In my years of programming, I’ve seen firsthand the transformation that comments bring to the readability and maintainability of code. Readability is key; Python’s design philosophy emphasizes it, and comments are a vital part of this principle. They serve as signposts, guiding future readers—including future you—through the logic and intent behind the code.

Simple in nature yet powerful in practice, comments explain why certain decisions were made in the coding process. Let’s be honest, even for seasoned developers, it’s all too easy to forget the purpose behind a complex function or a quick fix. Comments act as a reminder, preventing unnecessary reexamination of the code.

For teams, they’re even more crucial. Comments serve as a communication tool that enhances collaboration. You might be working on a module today, but tomorrow it could be someone else’s responsibility. With succinct comments peppered throughout the code, transitions between team members become seamless.

Beneath the surface, comments can also play a pivotal role in debugging and troubleshooting. By providing context to the blocks of code, they enable quick identification of potential problem areas. This not just speeds up the debugging process, but also helps in keeping it less stressful.

Lastly, when it comes to educational purposes, comments are gold. They turn code into an illustrative tutorial for less experienced programmers. I’ve used comments to teach coding concepts, and trust me, they can illustrate the flow of logic much better than some textbooks.

While it’s tempting to consider your present understanding as eternal, the reality is memories fade. Robust commenting makes sure that when you come back to a piece of code, it’s as if you never left. It’s all about writing code not just for machines to execute, but for humans to understand.

Best Practices for Writing Python Comments

When I approach the task of commenting my code, clarity and conciseness always take the front seat. Before typing out a comment, I make sure it adds value and isn’t stating the obvious. Here are a few golden rules I’ve picked up along my coding journey:

  • Keep it Relevant: Comments should directly relate to the adjacent code. I steer clear of generic observations and focus on the why, not the how.
  • Stay Up-to-Date: Outdated comments can mislead and confuse, so I’m vigilant about updating them whenever I tweak the code.
  • Match the Complexity: More intricate code blocks demand comprehensive comments. For simple lines, a short description or no comment at all often suffices.

In-line comments right beside a code statement offer immediate insight. For longer descriptions or discussions, I place block comments above the relevant section. When I write comments, I envision explaining the code to someone who’s unfamiliar with it, ensuring that I’m as clear as possible.

The magic of docstrings for functions, classes, and modules can’t be ignored in Python. They’re my go-to for providing an official description of a section of code. What’s convenient is that these can be accessed at runtime using tools like help().

  • Use """Triple double quotes""" for docstrings.
  • Start with a brief overview.
  • Include parameters, return values, and details on raised exceptions.

Consistency in commenting style aids readability and maintenance. Adopt a convention at the project’s onset or conform to the existing one if I’m joining a project midway. Sticking to style guides like PEP 8 ensures uniformity and adherence to community standards. Finally, I always consider the possibility of auto-generated documentation, aiming to craft comments that lend themselves well to tools such as Sphinx.

Leveraging comments effectively transforms my Python scripts into navigable, maintainable, and transferable pieces of code that resonate well beyond my personal use.

Types of Python Comments

In Python, comments can take several forms, each serving a different purpose. These varying types aid in code readability and maintenance by explaining what parts of the code do, why certain decisions were taken, and by providing metadata or disabling code.

Single-line comments are the most common and are constructed using the hash symbol (#). They’re ideal for brief explanations or for temporarily removing code during troubleshooting.

Here’s how you typically use them:

This is a single-line comment

print(“Hello, World!”) # This comment follows a statement
Multi-line comments, contrary to what the name suggests, aren’t natively supported in Python. However, you can achieve the same effect by using triple quotes (”’ or “””) although these are technically not comments but a string not assigned to a variable and therefore ignored at runtime.

Here's an example of multi-line comments:
This is an example of a multi-line string used as a comment
It can span multiple lines.
print("Multi-line comments example")
Inline comments sit on the same line as the code. They should be used sparingly, only when the code is not self-explanatory. The key is to keep them short and to the point to avoid clutter.

In Python, documentation strings (docstrings) serve as official documentation for a function, method, class, or module. They’re enclosed in triple quotes and should provide a clear understanding of the object’s purpose.

Example of a docstring:

def greet(name):
  Greet someone by their name.
  print("Hello, " + name)

Utilizing the correct type of comment for the given scenario enhances understandability and professionalism in the codebase. As you continue to write Python, pay attention to how each comment type can work to your advantage and practice recognizing situations where one is more suitable than another.

Remember, effective commenting is not about the quantity but the quality and relevance. When in doubt, choose clarity over cleverness and simplicity over complexity. Your future self and your team will thank you for it.

Commenting Styles in Python

When writing comments in Python, the style you choose plays a significant role in enhancing readability. You’ll commonly come across two commenting styles: block commenting and inline commenting.

Block commenting is when comments form a block of text above the code they describe. This approach works well for explaining complex algorithms or providing an overview of what the following code section will accomplish. These comments should be concise and focused on describing the intent behind the code. A typical block comment might look like this:

This function calculates the factorial

of a given number using recursion.

def factorial(n):
  # Base case: if n is 1, return 1
  if n == 1:
    return 1
    return n * factorial(n - 1)

In contrast, inline commenting is all about brevity and is used to provide quick, at-a-glance explanations of particular code lines. It’s important to use them sparingly to avoid clutter. Inline comments should be placed on the same line as the code after at least two spaces and should clarify the reasoning for specific operations or complex expressions. Here’s how an inline comment can be effectively used:

x = 10 # Initialize x to 10

While block comments aid in understanding sequences of code, inline comments demystify specific lines, making them complementary styles. Moreover, it’s crucial to maintain a consistent commenting style throughout your codebase to prevent comprehension difficulties. Consistency includes not just the placement of comments, but also the language used. For example, you should decide whether to write comments in an instructive style (e.g., “Initialize x to 10”) or a descriptive style (e.g., “x is initialized to 10”), and stick to it.

A key aspect of Python commenting is also regular updates. As your code changes, so should your comments to accurately reflect what the code does. Outdated comments can lead to confusion or misinterpretation, effectively diminishing the value of your documentation efforts.

Commenting Guidelines for Code Readability

When I’m writing code, code readability is always at the forefront of my mind. It’s not just about making the code work; it’s about making it understandable for others and my future self. Good comments are a vital component of readability. Here are some essential commenting guidelines I always follow to keep my code reader-friendly:

  • Keep Comments Relevant and Concise: Long-winded explanations can be more confusing than no comments at all. I aim to write comments that add value and are straight to the point.
  • Use Consistent Commenting Style: Whether it’s block or inline, choosing one style and sticking to it throughout the codebase helps maintain readability.
  • Avoid Commenting the Obvious: There’s no need to state what’s already clear from the code. I comment on the why, not the what.
  • Clarify Complex Code: Anytime code is not immediately understandable, I insert a comment to explain the logic. This is particularly helpful for complex algorithms or tricky bits of logic.
  • Keep Comments Up-To-Date: As I refactor and update the code, the comments must evolve alongside. Outdated comments can mislead and confuse, potentially leading to errors.

Properly commenting code is almost an art form. It requires a balance between being informative and being concise. When done well, comments illuminate the thought process behind the code, making it far more accessible. For example:

Calculate and return the factorial of a number

def factorial(num):
  # Base case: factorial of 0 or 1
  if num in (0, 1):
    return 1
  # Recursive case: num * factorial of num-1
    return num * factorial(num - 1)

In the example above, comments are used judiciously to explain the function’s purpose and the reasoning behind the recursive approach. By keeping the comments focused and purposeful, I provide clarity without overwhelming the reader with unnecessary details. As I continue to hone my coding skills, commenting remains a key part of my practice – ensuring anyone who crosses paths with my code can follow its rhythm and intent, without ever stumbling upon a jarring, superfluous block of text.

Tips for Effective Use of Python Comments

When writing Python code, I’ve found that effective comments can transform a snarl of code into a readable and maintainable script. Here are my top tips for leveraging the power of comments:

Be Timely and Proactive
I always try to comment my code as I write it. It’s tempting to think I’ll remember my thought process later, but experience tells me that’s often not the case. Commenting in the moment helps me maintain clarity not just for others but for my future self as well.

Focus on the Why, Not Just the How
Python’s syntax is often self-explanatory. What’s most valuable is context that the code can’t provide. I aim to explain why I chose a specific approach or what a complex block is designed to achieve. This additional clarity is invaluable when revisiting sections of code after some time.

Use Inline Comments Sparingly
Overcommenting can be as detrimental as under-commenting. I tend to use inline comments sparingly to avoid clutter. Instead, I’ll place comments above a block of code. This keeps my code clean and my guidance clear.

Adopt a Consistent Style

  • Descriptive variable and function names: I let them do the heavy lifting so comments can be minimal.
  • Block comments: I use them to describe larger sections of code and their overall purpose.
  • Inline comments: I reserve these for clarifying complex parts of a statement.

Consistency is key in making the comments feel like part of the code rather than an afterthought. As I maintain consistency, it becomes second nature to read and write comments effectively.

Remember, comments are for humans. Python won’t execute them, but they can make a huge difference in the execution of your project. By following these simple guidelines, I’ve made my code more accessible and easier to maintain.


Mastering the art of commenting is as crucial as the coding itself. I’ve shared how to enhance readability and why the ‘why’ behind your code matters. Remember, sparingly used inline comments can clarify complex sections, and consistency in your commenting approach can significantly improve code comprehension. Embrace these practices and you’ll see how they lead to more accessible and maintainable projects. After all, clear comments are the hallmark of a thoughtful programmer who values collaboration and future-proofing their work.