Lightweight tags

[schwern]

I would like to make use of Git::Raw in Gitpan, but it's missing support for lightweight tags. Gitpan needs to make a lot of tags and full, cryptographically secure, annotated tags are overkill. I realize they can be created with Git::Repository::Reference->create, but lightweight tags are not well integrated into the rest of Git::Raw.

I began to implement it, but ran into a problem. Git::Raw::Tag represents an annotated tag object. Lightweight tags do not appear to have a tag object, they're references to a commit.

Where I'm stuck in implementing lightweight tags is where they fit relative to annotated tags. Should they be left as references so Git::Raw::Reference->create_lightweight_tag() is a wrapper around Git::Raw::Reference->create("refs/tags/$name", $repo, $commit)?

Or should Git::Tag attempt to integrate them? I noticed there's a test in t/03-tag.t which appears to deliberately check that Git::Raw::Repository->tags does not see lightweight tags which is a bit confusing to command line users. I wonder if this is an undocumented quirk of git_tag_foreach, because git_tag_list does appear to return both annotated and lightweight tags, as evidenced in the libgit2 tag example.

What are your thoughts?

[jacquesg]

git_tag_foreach actually does return light-weight tags, Git::Raw is just ignoring it

STATIC int git_tag_foreach_cbb(const char *name, git_oid *oid, void *payload) {
    dSP;
    int rv = 0;
    git_object *tag;

    SV *cb_arg = NULL;
    git_foreach_payload *pl = payload;

    int rc = git_object_lookup(&tag, pl -> repo_ptr -> repository, oid, GIT_OBJ_ANY);
    git_check_error(rc);

    if (git_object_type(tag) != GIT_OBJ_TAG) {
        git_object_free(tag);

        return 0;
    }

The correct thing to do here is for a Git::Raw object to represent any type of tag, and add methods like is_lightweight etc. Let me see what I can do.

[schwern]

Thanks!

PS The urgency for Gitpan is considerably reduced, I used
Git::Raw::Reference to accomplish what I needed.

[jacquesg]

I'm actually looking right at this at the moment. Looks like the best I can do would be to improve the interface. A little bit weary of adding too much magic on top of libgit2, as it will just come back to bite in future (don't want to unnecessarily break compatibility in future).

[schwern]

What I would suggest is to leave Git::Raw as a thin wrapper around
libgit2. Then a separate module, using Git::Raw, makes it convenient.
This lets the work be separated, keeps Git::Raw flexible, and lets
multiple convenience implementations be written with different ideas
about what's convenient.

This offers a solution for lightweight tags. git_tag_foreach() and
git_tag_list() return all types of tags. If Git::Raw is supposed to be
a thin wrapper around libgit2 it shouldn't interfere and limit this
functionality. It should return all tags, as libgit2 does.

I see two ways forward...

1. Return Tag and Reference/Commit objects and let the caller figure it
   out. This is what libgit2 does.

2. Create a Git::Raw::Tag::Lightweight class which shares the interface
   of Git::Raw::Tag. Lightweight objects would be a delegation wrapper
   around Git::Raw::Commit and/or Reference objects. Most methods would
   work the same: lookup, owner, foreach, delete, id, name, target. Some
   would always return undef: message, tagger. is_lightweight() would be
   hard coded as appropriate.

I would suggest Git::Raw::Tag->foreach() is left as close to
git_tag_foreach() as possible, just return the objects as found as per

1. 2 would be implemented as a separate convenience method, or left as
   an exercise for another module.

[jacquesg]

Agree on 1. I'm busy with the changes so Git::Raw::Tag->foreach will return either a Git::Raw::Commit or Git::Raw::Reference object. I think I'll allow you to optionally specify which type of tags you're interested in, all, annotated or light-weight.

2 is really user specific, not something I would like to add to Git::Raw.

[jacquesg]

This should be better now :)

[jacquesg]

I've created a new release (https://metacpan.org/release/JACQUESG/Git-Raw-0.45), see if it works better for you.

[jacquesg]

Thanks for your input, let me know if you have more suggestions/problems.