pit - a Git implementation in Python

A from-scratch implementation of Git in Python. Supports the full object model, branching, merging, diffing, and SSH push/fetch to real GitHub repos -- all without depending on the git binary.

Install

pip install -e .

This makes the pit command available globally.

Quick start

pit init
echo "hello" > readme.txt
pit add readme.txt
pit commit -m "first commit"

Author identity

pit reads your identity from ~/.gitconfig (same file as git). If you already have git configured, it just works:

git config --global user.name "Your Name"
git config --global user.email "your@email.com"

Priority chain (same as git):

1. GIT_AUTHOR_NAME / GIT_AUTHOR_EMAIL env vars
2. GIT_COMMITTER_NAME / GIT_COMMITTER_EMAIL env vars
3. ~/.gitconfig [user] name / email
4. Error with instructions to configure it

Commands

Local

Command	What it does
pit init	Create a new .pit repository
pit hash-object <file>	Compute object SHA and store it
pit cat-file <sha>	Print the content of an object
pit add <path>	Stage a file or directory
pit write-tree	Write the index as a tree object
pit read-tree <sha>	Load a tree into the index
pit commit -m "msg"	Create a commit
pit log	Show commit history
pit show [sha]	Show commit + diff
pit status	Show working tree / index / HEAD state
pit diff [--cached] [commit]	Show differences
pit branch	List branches
pit branch <name> [start]	Create a branch
pit checkout <branch-or-sha>	Switch HEAD
pit tag <name> [sha]	Tag a commit
pit merge <commit>	Merge a commit into HEAD
pit merge-base <c1> <c2>	Find merge base
pit reset <commit>	Move HEAD to a commit
pit k	Visualize commit graph (requires Graphviz)

Remotes

Command	What it does
pit remote add <name> <url>	Store a named remote
pit remote list	List stored remotes
pit push <remote> <branch>	Push objects and update remote ref
pit fetch <remote>	Fetch objects and remote-tracking refs

Remote URLs support both forms:

pit remote add origin git@github.com:user/repo.git
pit push origin master

Or use a URL directly:

pit push git@github.com:user/repo.git master

What makes pit different

Everything is written from scratch -- no calls to the git binary. The components are:

• data.py -- Object storage (blob, tree, commit) with git-compatible hashing (type size\0content)
• base.py -- Core operations (add, commit, merge, diff tree walking, branch/tag management)
• pktline.py -- Git wire protocol pkt-line framing
• packfile.py -- Packfile read/write with REF_DELTA and OFS_DELTA support
• transport.py -- SSH transport: git-receive-pack (push) and git-upload-pack (fetch) protocol
• remote.py -- Dispatches between local filesystem and remote SSH operations
• diff.py -- Tree diff, blob merge
• cli.py -- Command-line interface

Tests

python -m pytest tests/