mygit – A Minimal Version Control System in Python

mygit is a simplified, command-line version control system built using Python. It mimics core functionalities of Git including initializing repositories, staging files, committing changes, creating branches, and checking out commits or branches.

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🧠 Project Summary

This project was built as part of Week 5 of a summer learning program to understand how version control systems like Git work under the hood. It was designed to reinforce core concepts like:

• File system operations
• Hashing and object storage
• Commit tracking and parent-child relationships
• HEAD pointer logic
• Branching and checkout mechanisms

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🚀 Features Implemented

✅ mygit init

Initializes a .mygit/ directory with folders for:

• objects/ – for storing blob hashes
• commits/ – to track commit metadata
• refs/heads/ – to store branch pointers
• HEAD – points to the current branch or commit

✅ mygit add <filename>

Stages the file by:

• Hashing the content
• Saving it in .mygit/objects/
• Recording it in .mygit/index

✅ mygit commit -m "message"

Commits all staged files by:

• Creating a metadata file in .mygit/commits/
• Linking to the parent commit
• Updating the current branch HEAD

✅ mygit branch

Lists all available branches in refs/heads/
Also shows the current branch using *.

✅ mygit checkout <commit-hash>

Checks out a specific commit by:

• Restoring file contents to working directory
• Updating HEAD to point directly to the commit

✅ mygit checkout <branch-name>

Switches to a branch by:

• Reading the commit hash pointed to by refs/heads/<branch>
• Restoring files from that commit
• Updating HEAD to point to ref: refs/heads/<branch>

✅ mygit checkout -b <branch-name>

Creates a new branch from the current commit and switches to it.

✅ mygit log

Displays commit history by traversing parent pointers from HEAD.

✅ mygit status

Shows staged files, untracked files, and file modifications (basic).

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🛠 Folder Structure

mygit/
├── main.py
├── src/
│ ├── add.py
│ ├── branch.py
│ ├── checkout.py
│ ├── commit.py
│ ├── init.py
│ ├── log.py
│ └── status.py
└── .mygit/
├── objects/
├── commits/
├── refs/
│ └── heads/
└── HEAD

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📦 Example Commands

python main.py init
python main.py add test.txt
python main.py commit -m "Initial commit"
python main.py branch
python main.py checkout -b dev
python main.py commit -m "Dev changes"
python main.py checkout master

📌 Key Learnings

• How Git internally manages objects, branches, and commits
• Implementing a simplified object database using SHA1 hashes
• File restoration logic through checkout
• Tracking changes with commit ancestry
• Simulating HEAD and refs behavior

⚙️ Limitations

• No support for merge or conflict resolution
• File rename tracking not implemented
• status is basic (no diff comparison)
• Does not support remote pushing/pulling

This project gave hands-on experience with how Git works internally and significantly improved understanding of version control principles. All core functionalities were implemented from scratch using only Python’s standard library and file system.