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Show HN: Pygit – Just enough git to push itself to GitHub

208 points by benhoyt 10y ago

rpeden 10y ago
Nice work! I love projects like this, because I think most of us would benefit from re-implementing our dev tools (at least partially) to develop a better understanding of how they work.
- pacaro 10y ago
  Traditionally some of the trade apprenticeships started with the new apprentice making their own tools. When I took a molecular cell biology class in college, the first series of labs involved disassembling and reassembling the bench microscopes that we would be using for the rest of the course (they were close to maxing out on optical resolution, the faculty couldn't afford to replace a broken one) As an engineer I enjoy making my own tools, sometimes a little too much
  - heywire 10y ago
    Similarly, when I got my first job as a PC tech at a locally-owned computer shop, my first task was to assemble my own "bench" PC for testing various components.
- abecedarius 10y ago
  Agreed, it looks great. More in that vein, for Python bytecode compiling and running: https://github.com/darius/tailbiter https://github.com/darius/tailbiter -- I can't quite resist mentioning it since I gave it a similar tag line, "just enough Python to Python in Python".
BackwardSpy 10y ago
Nice work! This seems like it could be a fun weekend project.
dmytrish 10y ago
Exercises like this are very educational for taking magic away from version control tools. Some time ago I did a similar exercise in Haskell: https://github.com/EarlGray/omit https://github.com/EarlGray/omit (it also took about 500 lines of unnecessarily dense Haskell), implementing barebone functionality of `git log`, `git add`, `git commit`, `git status`, `git diff` (using an existing Haskell diff library). It was eye-opening how simple the concepts of git are. On the other hand, the most interesting parts of git are still left out: branches, merges, conflict resolution, remote sync. I'm wondering how many more lines are needed for this.
- AtticusTheGreat 10y ago
  The thing is, all of these details are implemented in the git command line tool, not in a library. So it is pretty difficult to write a tool that works exactly the same way the command line tool does, or if you do manage to do it, it'll be fragile since the command line tool could change behavior at any time.
- hdhzy 10y ago
  > It was eye-opening how simple the concepts of git are. Exactly! Sometimes I'm bewildered how complex git porcelain (CLI interface) is compared to the basic building blocks. Usually when I want to do something complex in git I think of how I want the structure to look like and then figure out which command does that ("was it git reset --soft or git stash --keep-index that did X?"). Now when I'm thinking about it I usually imagine states (like DOM trees). I see current state and the state I want to have the repo in (commits, working directly, index). What I'm missing here is a React-like reconciler that will transform one into other.
- federicotdn 10y ago
  I have a similar project, also using Haskell: https://github.com/federicotdn/hvc https://github.com/federicotdn/hvc
wooptoo 10y ago
Great article! An equally educational one for a torrent client in C# https://news.ycombinator.com/item?id=12035568 https://news.ycombinator.com/item?id=12035568
nkantar 10y ago
Neat! My local Python group had a talk on something like this last year: https://github.com/glenjarvis/explore_git_internals https://github.com/glenjarvis/explore_git_internals
deleted 10y ago
[deleted]
webaholic 10y ago
Nice. I wonder if anyone tried doing the same in rust?
- acqq 10y ago
  I don't think it would be of any strategic advantage? The promise of Rust is to be once better than C not better than Python. Nit to mention all the needed libraries.
  - saghm 10y ago
    I'm a bit confused by this logic; git is written in C, so if Rust is supposed to be "better then C", then wouldn't it make perfect sense to write it in Rust?
    - acqq 10y ago
      In general yes, it would benefit Rust, long term. But for the purpose of this article, no. The result would at this moment be much bigger than 500 lines, which wouldn't have any power of a short example.
    - deleted 10y ago
      [deleted]
- steveklabnik 10y ago
  https://github.com/libgit2/libgit2/pull/3540 https://github.com/libgit2/libgit2/pull/3540 might be of interest (note that it's over a year old at this point)
chubot 10y ago
Related: http://gitlet.maryrosecook.com/ http://gitlet.maryrosecook.com/ Gitlet is an implemention of Git in JavaScript. https://maryrosecook.com/blog/post/git-from-the-inside-out https://maryrosecook.com/blog/post/git-from-the-inside-out
thaeli 10y ago
This feels like the most appropriate way to make a quine of a VCS tool.
zimbatm 10y ago
I wonder how fast it would propagate if it was able to inject itself into existing repos and hook itself to package.json and other installer scripts.
thinkpad20 10y ago
Super cool project! I hope this isn't taken as a frivolous or mean-spirited comment, but the code samples on the blog would be much more readable with some kind of syntax highlighting.
- benhoyt 10y ago
  Good call! Thanks to Jekyll and Rouge, I added some light syntax highlighting.
raziel2p 10y ago
I'd reconsider the name, I'm sure pretty it will cause confusion with pygit2.
krallja 10y ago
See also Dulwich, a pure-Python Git implementation https://github.com/jelmer/dulwich https://github.com/jelmer/dulwich

208 points by benhoyt 10y ago

Nice work! I love projects like this, because I think most of us would benefit from re-implementing our dev tools (at least partially) to develop a better understanding of how they work.

pacaro 10y ago
Traditionally some of the trade apprenticeships started with the new apprentice making their own tools. When I took a molecular cell biology class in college, the first series of labs involved disassembling and reassembling the bench microscopes that we would be using for the rest of the course (they were close to maxing out on optical resolution, the faculty couldn't afford to replace a broken one) As an engineer I enjoy making my own tools, sometimes a little too much
- heywire 10y ago
  Similarly, when I got my first job as a PC tech at a locally-owned computer shop, my first task was to assemble my own "bench" PC for testing various components.
abecedarius 10y ago
Agreed, it looks great. More in that vein, for Python bytecode compiling and running: https://github.com/darius/tailbiter https://github.com/darius/tailbiter -- I can't quite resist mentioning it since I gave it a similar tag line, "just enough Python to Python in Python".

BackwardSpy 10y ago

Nice work! This seems like it could be a fun weekend project.

dmytrish 10y ago

Exercises like this are very educational for taking magic away from version control tools. Some time ago I did a similar exercise in Haskell: https://github.com/EarlGray/omit https://github.com/EarlGray/omit (it also took about 500 lines of unnecessarily dense Haskell), implementing barebone functionality of `git log`, `git add`, `git commit`, `git status`, `git diff` (using an existing Haskell diff library). It was eye-opening how simple the concepts of git are. On the other hand, the most interesting parts of git are still left out: branches, merges, conflict resolution, remote sync. I'm wondering how many more lines are needed for this.

AtticusTheGreat 10y ago
The thing is, all of these details are implemented in the git command line tool, not in a library. So it is pretty difficult to write a tool that works exactly the same way the command line tool does, or if you do manage to do it, it'll be fragile since the command line tool could change behavior at any time.
hdhzy 10y ago
> It was eye-opening how simple the concepts of git are. Exactly! Sometimes I'm bewildered how complex git porcelain (CLI interface) is compared to the basic building blocks. Usually when I want to do something complex in git I think of how I want the structure to look like and then figure out which command does that ("was it git reset --soft or git stash --keep-index that did X?"). Now when I'm thinking about it I usually imagine states (like DOM trees). I see current state and the state I want to have the repo in (commits, working directly, index). What I'm missing here is a React-like reconciler that will transform one into other.
federicotdn 10y ago
I have a similar project, also using Haskell: https://github.com/federicotdn/hvc https://github.com/federicotdn/hvc

wooptoo 10y ago

Great article! An equally educational one for a torrent client in C# https://news.ycombinator.com/item?id=12035568 https://news.ycombinator.com/item?id=12035568

nkantar 10y ago

Neat! My local Python group had a talk on something like this last year: https://github.com/glenjarvis/explore_git_internals https://github.com/glenjarvis/explore_git_internals

deleted 10y ago

[deleted]

webaholic 10y ago

Nice. I wonder if anyone tried doing the same in rust?

acqq 10y ago
I don't think it would be of any strategic advantage? The promise of Rust is to be once better than C not better than Python. Nit to mention all the needed libraries.
- saghm 10y ago
  I'm a bit confused by this logic; git is written in C, so if Rust is supposed to be "better then C", then wouldn't it make perfect sense to write it in Rust?
  - acqq 10y ago
    In general yes, it would benefit Rust, long term. But for the purpose of this article, no. The result would at this moment be much bigger than 500 lines, which wouldn't have any power of a short example.
  - deleted 10y ago
    [deleted]
steveklabnik 10y ago
https://github.com/libgit2/libgit2/pull/3540 https://github.com/libgit2/libgit2/pull/3540 might be of interest (note that it's over a year old at this point)

chubot 10y ago

Related: http://gitlet.maryrosecook.com/ http://gitlet.maryrosecook.com/ Gitlet is an implemention of Git in JavaScript. https://maryrosecook.com/blog/post/git-from-the-inside-out https://maryrosecook.com/blog/post/git-from-the-inside-out

thaeli 10y ago

This feels like the most appropriate way to make a quine of a VCS tool.

zimbatm 10y ago

I wonder how fast it would propagate if it was able to inject itself into existing repos and hook itself to package.json and other installer scripts.

thinkpad20 10y ago

Super cool project! I hope this isn't taken as a frivolous or mean-spirited comment, but the code samples on the blog would be much more readable with some kind of syntax highlighting.

benhoyt 10y ago
Good call! Thanks to Jekyll and Rouge, I added some light syntax highlighting.

raziel2p 10y ago

I'd reconsider the name, I'm sure pretty it will cause confusion with pygit2.

krallja 10y ago

See also Dulwich, a pure-Python Git implementation https://github.com/jelmer/dulwich https://github.com/jelmer/dulwich