conda-forge recipe

[MatthiasKohl]

For my project, it would be great to have nanobind available through conda.
This is slightly different compared to pybind since for that only headers are needed so it's easy to manage through a build system.

OTOH, for nanobind, since the library is necessary, it's cleaner to have it properly installed (even though I'm aware that it is usually linked statically into the build).

So are you OK if I submit a conda recipe to the conda-forge feedstock?
I think the license works well for this, and I'd simply attribute the conda recipe itself to this project as well.

[wjakob]

Conda to me is an elegant way of distributing Python packages with native extension libraries and depending on precompiled binaries.

What would be the point of a conda-forge recipe for nanobind, which would only be distributed in source form?

AFAIK, these days you can mix and match and just stick a PyPI line

  - pip:
      - nanobind

into your environment.yml. In that case, a separate conda-forge distribution channel would just add complications.

I haven't used conda in a long time and am happy to be proven wrong. At least currently don't understand the point of the request.

[MatthiasKohl]

Yes, you can do this in environment.yml for creating a new environment, but you cannot put this in a conda recipe for the build dependencies of a conda package.

Now, to work around this, it's easy enough to have git as a build dependency, then clone the repo and install it during build, but I think this is less elegant since we actually have to correctly install the library.
This is different from pybind where we can simply put the headers somewhere and don't care about linking in a library at all.

[wjakob]

Ok, I understand. Feel free to make such a recipe -- it would be great if you could give me co-maintainer access to the repository.

[MatthiasKohl]

Sure I can do that.

[MatthiasKohl]

@wjakob : I've added this PR (conda-forge/staged-recipes#20755) for the conda-forge recipe. I'll update it slightly to ensure we have python version >= 3.8.
Other than that, it's a very simple recipe and it just uses the GitHub tarball one gets from tagging versions here.

One thing I would need you to do is to comment on that PR that you are willing to be a maintainer for the recipe.
In this case, this would mainly mean bumping the version when necessary, since it's unlikely the package will break since it just uses pip install.
Once the PR goes through, it will automatically create a new repo on which we will both be added as maintainers and which will contain the actual recipe used for conda-forge.

[MatthiasKohl]

@wjakob : I re-tested the conda package and it's not working because the source/releases from github don't contain the robin_map sub-module. I didn't catch this before because my test environment wasn't clean, and had the sub-module already.

Would it be possible for you to just add those packages as additional tarballs to the releases here?
Unfortunately, github doesn't allow you to do this automatically, see dear-github/dear-github#214 : this is quite annoying for a project like this one which has sub-modules and only a source release.
You basically have to do a git clone --recurse-submodules, then checkout the right tag, create a tarball and upload it for every new release. In the linked issue, there are github actions which would do this automatically, but I'm not sure how to set this up to run whenever a new release/tag is added.

[MatthiasKohl]

plus, there are automated tools from conda-forge which update versions, see e.g. conda-forge/nanobind-feedstock#1

I'm not sure whether those would work with the wheel, but I guess we'll see

[wjakob]

Hi @MatthiasKohl ,

have you checked this? -> https://docs.conda.io/projects/conda-build/en/latest/resources/define-metadata.html#source-from-multiple-sources

Apparently multiple sources are legal for a conda-forge recipe. This might be useful to fetch the tagged commit from nanobind and a the robin-map dependency.

Best,
Wenzel

[wjakob]

I haven't followed closely and wanted to follow up: what is the status of the conda-forge package? Does it work correctly?

[MatthiasKohl]

Hi @wjakob, sorry I completely missed your previous message.
As of now, the conda package is working since I modified the install to use git to clone and checkout the robin map repo. Git is cross platform and so this can be done easily without making the build+install process within conda complicated.
In principle, multiple sources could be an option as well but I'm not sure if conda-forge allows this: they have strict rules about how the recipes should be written because of a lot of automation for updating versions or updating the recipes for a future format etc.
So I think the current solution is OK

[wjakob]

Great, I am happy to hear it. Thank you for setting this up.