Code Commenting Checklists

Code Commenting Checklists

When to Use This Skill

• Writing or reviewing code comments
• Conducting code reviews
• Establishing code quality standards
• Onboarding new developers to commenting practices
• Preparing code for maintenance or handoff

General Comment Techniques Checklist

Apply this checklist to ensure overall comment quality:

• Understandability: Can others immediately pick up the code and understand it?
• Intent explanation: Does the comment explain the intent or summarize functionality, rather than repeating the code?
• PPP usage: Was Pseudocode Programming Process used to reduce commenting time?
• Refactoring first: Was tricky code rewritten instead of just adding comments?
• Currency: Are comments up-to-date with the current code?
• Clarity: Are comments clear and correct?
• Maintainability: Does the comment style allow easy modification?

Data Declaration Comment Rules

Apply this checklist when declaring variables, constants, and data structures:

• Units: Are units of measurement commented? (e.g., // milliseconds, // kilograms)
• Value ranges: Are valid ranges for numeric data commented?
• Encoding meanings: Are coded values explained? (e.g., status codes, enum values)
• Input constraints: Are restrictions on input data documented?
• Flag documentation: Are flags documented to the bit level?
• Global variables (declaration): Is each global variable commented at its declaration?
• Global variables (usage): Is each global variable identified at every use via naming convention, comment, or both?
• Magic numbers: Are magic numbers replaced with named constants rather than just documented?

Program Structure and File Comment Rules

Apply this checklist for subprograms, functions, classes, and files:

• Subprogram purpose: Is the purpose of each subprogram commented?
• Subprogram details: Are additional facts included when appropriate?
  • Input and output data
  • Interface assumptions
  • Limitations and constraints
  • Error correction behavior
  • Global effects
  • Algorithm sources
• Control structures: Is each control statement commented?
• Complex structure endings: Are long/complex control structure endings commented, or simplified to eliminate the need?
• Program overview: Is there a short document providing an overall view of program organization?
• File purpose: Is the purpose of each file described?
• Author information: Does the file include author name, email, and phone number?

Usage Guidelines

During Code Writing

1. Write comments as you write code
2. Apply relevant checklist items before committing
3. Review against all applicable checklists during self-review

During Code Review

1. Use checklists as review criteria
2. Flag missing items for correction
3. Track common violations for team improvement

For Legacy Code

1. Prioritize critical sections first
2. Focus on data declarations and public interfaces
3. Document complex logic before simple code

Common Violations to Watch

Data Declarations

// BAD: No units or range
let timeout = 5000;

// GOOD: Complete documentation
// Timeout in milliseconds for API calls (range: 1000-30000)
let timeout = 5000;

Magic Numbers

# BAD: Magic number documented but not replaced
# Days in a year (365)
days = 365

# GOOD: Named constant
DAYS_IN_YEAR = 365
days = DAYS_IN_YEAR

Global Variables

// BAD: Global used without identification
public static int count;
// ... later ...
count++;

// GOOD: Clearly identified at usage
public static int g_userCount;  // Global: total active users
// ... later ...
g_userCount++;  // Global: increment active user count

Control Structures

// BAD: Complex structure without comment
for (let i = 0; i < items.length; i++) {
  for (let j = i + 1; j < items.length; j++) {
    if (items[i] > items[j]) {
      // swap
    }
  }
}

// GOOD: Commented or simplified
// Bubble sort: compare each pair and swap if out of order
for (let i = 0; i < items.length; i++) {
  for (let j = i + 1; j < items.length; j++) {
    if (items[i] > items[j]) {
      swap(items, i, j);
    }
  }
}