Hello, Maxim Cournoyer <maxim.courno...@gmail.com> skribis:
> Ludovic Courtès <l...@gnu.org> writes: [...] >> Why does the importer favor .whl in the first place? Is it supposed to >> be more accurate or more widespread or something? > > Yes, the METADATA file from the binary wheel is a better place to look > than the source egg-info requires.txt file. In my commit 01589acc5e1, I > simplified a comment that used used to read as: > > - ;; First, try to compute the requirements using the wheel, since that is > the > - ;; most reliable option. If a wheel is not provided for this package, try > - ;; getting them by reading either the "requirements.txt" file or the > - ;; "requires.txt" from the egg-info directory from the source tarball. Note > - ;; that "requirements.txt" is not mandatory, so this is likely to fail. > + ;; First, try to compute the requirements using the wheel, else, fallback > to > + ;; reading the "requires.txt" from the egg-info directory from the source > + ;; tarball. > > The wheel (.whl) binary format is well specified as PEP 427 [0] and is > what pip primarily uses for installing Python packages, making it a very > reliable source of metadata. The Python egg is the predecessor of the > wheel, and can be considered obsolete, which explains why it's used as a > fallback. Oh, I see. > Perhaps it'd be best to raise the issue to the package maintainers and > have them specify their metadata correctly? Going back to the example at the beginning of this thread, what ‘guix import pypi tablib’ produces is missing ‘python-setuptools-scm’. Indeed, ‘METADATA’ doesn’t mention it. Is it really a bug on their side, or is it something peculiar about Guix packaging? Perhaps ‘python-setuptools-scm’ should be provided more or less by default? > Having the code you wrote to allow importing optional dependencies is > still a nice (optional) option to have though. It was originally left > out based on comments from Ricardo that it wouldn't make a good default > due to raising the packaging effort. OK. Looking at <https://www.python.org/dev/peps/pep-0345/>, the ‘METADATA’ format apparently doesn’t support optional dependencies anyway (which makes sense, because Wheels are a binary format), so perhaps that idea was misguided. (However ‘METADATA’ defines ‘Requires-External’, which the importer could usefully interpret!) WDYT? Ludo’.
