Explaining code changes

Explaining Code Changes - Markdown Format Guide

This guide outlines best practices for explaining code changes using Markdown, geared towards software professionals. Clear and concise change explanations are crucial for code reviews, team collaboration, and future maintainability.

I. Core Principles

• Focus onWhy, not justWhat.The code itself shows what changed; your explanation should focus on why.
• Be concise.Respect reviewers’ time.
• Use context.Provide enough background to understand the change.
• Link to issues or tickets.Reference Jira, GitHub, etc.
• Highlight key areas.Draw attention to important logic.
• Consider the audience.Adjust technical depth accordingly.

II. Structure for Explaining Code Changes

1. Title / Summary

Use a short, descriptive title starting with a verb. Example:Fix: Prevent crash on empty input

2. Context & Motivation

• Problem:What was broken or missing
• Solution:High-level explanation of the fix
• Issue Link:Reference the tracking ticket

Fix: Prevent crash when processing empty data files

This change fixes a crash caused by attempting to read data
from an empty file. The application previously assumed that
at least one record always existed.

An explicit empty check was added to prevent the crash.

Resolves issue #1234

3. Detailed Changes

File: src/com/example/data/DataLoader.java

The change affects theloadData()method, which previously accessed the first element without validation.

Before:

public List<String> loadData(String filePath) {
    List<String> data = Files.readAllLines(Paths.get(filePath));
    return data.get(0);
}

After:

public List<String> loadData(String filePath) {
    List<String> data = Files.readAllLines(Paths.get(filePath));
    if (data.isEmpty()) {
        return Collections.emptyList();
    }
    return data;
}

This change prevents anIndexOutOfBoundsExceptionby safely handling empty files.

4. Testing & Verification

• Unit Testing:Added a test to verify empty file handling.
• Manual Testing:Tested with multiple empty input files.

Verification Steps

1. Create an empty text file.
2. Run the application.
3. Load the empty file.
4. Confirm the application does not crash.

5. Potential Risks & Considerations

• Side Effects:None identified
• Future Improvements:Add logging for empty inputs
• Dependencies:No new dependencies added

III. Formatting Best Practices

• Use headings to structure explanations clearly
• Use bullet points for readability
• Highlight key terms usingboldtext
• Use code blocks for examples
• Keep explanations short and focused

IV. Example: Complete Change Explanation

Feature: User profile picture upload

This change allows users to upload a profile picture
to personalize their profile.

Related ticket: PROJ-123

File: src/com/example/user/UserProfile.java

Added a new field to store the profile image URL.

private String profilePictureUrl;

File: src/com/example/api/UserController.java

Updated the profile update endpoint to accept image uploads and store the uploaded image URL.

@PostMapping("/profile")
public ResponseEntity<UserProfile> updateProfile(...) {
    if (file != null && !file.isEmpty()) {
        String url = uploadProfilePicture(file);
        userProfile.setProfilePictureUrl(url);
    }
}

Testing Summary

• Unit tests added for upload logic
• Integration tests verified API workflow
• Manual testing confirmed UI behavior

Risks & Notes

• Monitor image storage usage
• Enforce file size limits

Following this structure helps teams communicate code changes clearly and maintain a high-quality codebase.