Python Code Commenting Standards: The Practical Guide (With Copy-Paste Prompts)
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Python Code Commenting Standards: The Practical Guide (With Copy-Paste Prompts)

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TL;DR

  • PEP 8 is the gold standard for Python code commenting—use it as your North Star.
  • Good comments clarify ‘why’, not just ‘what’—avoid restating code.
  • Inline, block, and docstring comments all have specific best practices.
  • Real-world examples and do/don’t tables below make standards actionable.
  • Founders and teams: Use the included ChatGPT prompts to review or improve your code comments instantly.

The Real Reason Commenting Standards Matter

If you’ve ever inherited a Python codebase—yours or someone else’s—you know the pain of cryptic, outdated, or missing comments. As a founder, you might not write every line, but you are responsible for maintainability, onboarding, and code quality across your team.

Poorly-commented code is expensive:

  • Slows down new hires (or future you)
  • Makes bug-hunting a nightmare
  • Risks security and compliance issues

Yet, over-commenting (or commenting the obvious) can clutter your code and waste time. The key is knowing what, where, and how to comment—and making it a habit across your team.

The Only Python Commenting Standards You (and Your Team) Need

1. Types of Comments in Python (with Examples)

a. Inline Comments

  • Purpose: Brief notes on tricky logic, exceptions, or non-obvious lines.
  • Format: Start with #, two spaces after code.
result = fetch_user_data(user_id)  # May raise ValueError if user not found

b. Block Comments

  • Purpose: Explain a section, decision, or workaround.
  • Format: Each line starts with #, indented at code level, blank line before block.
# Check if user is active and has completed onboarding.
# This prevents sending emails to unverified users.
if user.is_active and user.onboarding_complete:
    send_welcome_email(user)

c. Docstrings

  • Purpose: Document modules, classes, functions (what it does, not how).
  • Format: Triple double-quotes, first line summary, optional details after.
def calculate_total(order):
    """
    Returns the total price for an order, including tax.
    Args:
        order (Order): The order object.
    Returns:
        float: Total price with tax.
    """
    ...

2. PEP 8: The Official Standard (in Plain English)

PEP 8 is Python’s official style guide. Here’s what it says about comments:

DoDon’t
Make comments complete sentences.Restate the code (“Increment x by 1” for x += 1)
Update comments when you update code.Leave outdated comments—they confuse everyone.
Use docstrings for all public functions/classes.Use comments to explain every line.
Capitalize the first word, use proper punctuation.Write in all lowercase, skip periods.
Keep comments concise and relevant.Insert jokes, opinions, or apologies.

3. How to Actually Write Useful Comments (Copy These Prompts)

Want to level up your code comments (or your team’s)? Here are some ChatGPT prompts to try:

For Reviewing Existing Code:

Review the following Python code for commenting standards. Suggest improvements based on PEP 8 and best practices, focusing on clarity and usefulness. 
[PASTE YOUR CODE HERE]

For Writing Block Comments:

Summarize the purpose and logic behind this code block in two clear sentences suitable for a Python block comment:
[PASTE CODE BLOCK]

For Docstring Generation:

Generate a concise docstring for this Python function, following PEP 257 and Google style:
[PASTE FUNCTION]

For Team-Wide Comment Consistency:

Create a checklist for Python code reviews focused on commenting standards, based on PEP 8. Highlight common mistakes and what to look for.

4. Commenting Standards: Python vs. Java and Google Style

  • Python: Emphasizes docstrings, minimal but meaningful comments.
  • Java: Tends to use Javadoc, more verbose, and expects every method to be commented.
  • Google Style (for Python): Builds on PEP 8, prefers Google-style docstrings, stricter on format.

Takeaway: Stick with PEP 8 + docstrings, but if collaborating with external teams, clarify which docstring format (Google, NumPy, reStructuredText) you’ll use.

5. Bonus: Downloadable Commenting Cheat Sheet

Final Thoughts & Next Steps

Don’t treat commenting as a chore. It’s an investment in your team’s sanity and your product’s future. Set a standard, automate reviews, and leverage tools like ChatGPT to make it effortless.

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Have a codebase horror story (or a tip)? Drop it in the comments below!