Re: libgit2 - a true git library

Shawn O. Pearce wrote:

Having looked briefly at the code, I've got a couple of comments:
* GIT_EXTERN() does nothing. Ever. It's noise and should be removed.
  Instead it would be better to have GIT_PRIVATE(), which could
  set visibility to "internal" or "hidden", meaning the symbol it's
  attached to can be used for lookups when creating a shared library
  but won't be usable from programs linking to that shared library
  (visibility-attributes have zero effect on static libraries). At
  least on all archs anyone really cares about.
* Prefixing the files themselves with git_ is useless and only leads
  to developer frustration. I imagine we'd be installing any header
  files in a git/ directory anyway, so we're gaining absolutely
  nothing with the git_ prefix on source-files.

Apart from that, it seems you've been designing a lot rather than trying to use the API to actually do something. It would, imo, be a lot better to start development with adding functionality shared between all programs and then expand further on that, such as incorporating all functions needed for manipulating tags into the library and then modify existing code to use the library to get tag-ish things done. That would also mean that the library would quickly get used by core git, as once a certain part of it is complete patches can be fitted to the library rather than to the current non-libish dying() functions.

I also think it's quite alright to not strive *too* hard to make all functions thread-safe, as very few of them will actually need that. It's unlikely that a user program will spawn one thread to write a lot of tags while another is trying to parse them, for example.

By adding an init routine that determines the workdir and the gitdir, one could start using the library straight away.

int git_init(const char *db, const char *worktree)
{
    if (git_set_db_dir(db))
        return -1;
    git_set_worktree((worktree))
        return -1;

    return 0;
}

and already you have a some few small helpers that are nifty to to have around: int git_is_gitdir(const char *path); /* returns 1 on success */ int git_has_gitdir(const char *path); /* returns 1 on success */ const char *git_mkpath(const char *fmt, ...)

This way one will notice rather quickly what's needed (making it easy to keep a more-or-less public TODO available, with small stuff on it for the most part), and one can then go look for it in the existing git code and, if possible, convert stuff or, best case scenario, steal it straight off so that more apps can benefit from tried and tested code.