Don't be afraid of extras. They have not been PEP'd but are required for a useful Python packaging system. install_requires is just a shorthand for extras with the "" empty string as their name. Too bad we couldn't agree on ; vs : as the delimiter though.
On Thu, Aug 31, 2017 at 2:04 PM Nathaniel Smith <n...@pobox.com> wrote: > On Thu, Aug 31, 2017 at 8:41 AM, Chris Barker - NOAA Federal > <chris.bar...@noaa.gov> wrote: > > The package manager should manage the package, not built it, or change > it. > > > > Surely the build system should know how to correctly name the wheel it > builds. > > It's probably worth mentioning the specific problem that motivated pip > to start doing this. > > It used to be standard, and is still quite common, for setup.py > scripts to contain stuff like: > > install_requires = [...] > if sys.version_info < (3, 4): > install_requires += [...] > if platform.python_implementation() == "PyPy": > install_requires += [...] > > setup(..., install_requires=install_requires) > > This kind of logic in setup.py worked fine in the old days when all > you did was 'setup.py install', but then wheels came along and > retroactively turned lots of setup.py scripts from working into > broken. The problem is that with this kind of setup.py, setuptools has > *no idea* that the install_requires you gave it would have been > different if you had run setup.py with a different version of Python, > so when it has to assign Python tags to a built wheel it guesses wrong > and uses ones that are too general. > > The right way to do this is to use PEP 508 environment markers: > https://www.python.org/dev/peps/pep-0508/#environment-markers > or the non-standard extras hack: > > https://wheel.readthedocs.io/en/latest/#defining-conditional-dependencies > Both of these let you export the whole requirements-choosing logic > into the wheel metadata, so that it can be evaluated at install time > instead of build time. > > But it will take a while for existing setup.py files transition to > using those, and in the mean time pip can't assume that a random wheel > generated by 'setup.py bdist_wheel' has accurate Python tags. > > Hopefully new legacy-free backends will get this right from the start. > For example flit makes it impossible to get this wrong. > > -n > > -- > Nathaniel J. Smith -- https://vorpus.org > _______________________________________________ > Distutils-SIG maillist - Distutils-SIG@python.org > https://mail.python.org/mailman/listinfo/distutils-sig >
_______________________________________________ Distutils-SIG maillist - Distutils-SIG@python.org https://mail.python.org/mailman/listinfo/distutils-sig
