clean-code

Clean Code Skill

Iron Law: Before applying any principle, READ the relevant source file first. Do not refactor or flag issues based on memory — verify the actual code (file:line) before making any claim.

This skill embodies the principles of "Clean Code" by Robert C. Martin (Uncle Bob). Use it to transform "code that works" into "code that is clean."

Core Philosophy

"Code is clean if it can be read, and enhanced by a developer other than its original author." — Grady Booch

When to Use

• Writing new code: Ensure high quality from the start.
• Reviewing Pull Requests: Provide constructive, principle-based feedback.
• Refactoring legacy code: Identify and remove code smells.
• Improving team standards: Align on industry-standard best practices.

1. Meaningful Names

• Use Intention-Revealing Names: elapsedTimeInDays instead of d.
• Avoid Disinformation: Don't use accountList if it's actually a Map.
• Make Meaningful Distinctions: Avoid ProductData vs ProductInfo.
• Use Pronounceable/Searchable Names: Avoid genymdhms.
• Class Names: Use nouns (Customer, WikiPage). Avoid Manager, Data.
• Method Names: Use verbs (postPayment, deletePage).

2. Functions

• Small: Functions should be shorter than you think.
• Do One Thing: A function should do only one thing, and do it well.
• One Level of Abstraction: Don't mix high-level business logic with low-level details (like regex).
• Descriptive Names: isPasswordValid is better than check.
• Arguments: 0 is ideal, 1-2 is okay, 3+ requires a very strong justification — introduce a parameter object.
• No Side Effects: Functions shouldn't secretly change global state.

3. Comments

• Don't Comment Bad Code — Rewrite It: Most comments are a sign of failure to express in code.
• Explain Yourself in Code:

  # BAD: comment explains intent that code should express
  if employee.flags & HOURLY and employee.age > 65:
  
  # GOOD: code expresses intent directly
  if employee.isEligibleForFullBenefits():
  

• Good Comments: Legal, informative (regex intent), clarification (external library behavior), TODOs (with ticket).
• Bad Comments: Mumbling, redundant, misleading, mandated, noise, position markers.