The subtle issue is of course performance if you get too cozy with this pattern...
On Wed, May 6, 2020 at 1:59 PM Nathaniel Smith <n...@pobox.com> wrote: > On Wed, May 6, 2020 at 7:52 AM Paul Ganssle <p...@ganssle.io> wrote: > > > > As part of PEP 399, an idiom for testing both C and pure Python versions > of a library is suggested making use if import_fresh_module. > > > > Unfortunately, I'm finding that this is not amazingly robust. We have > this issue: https://bugs.python.org/issue40058, where the tester for > datetime needs to do some funky manipulations to the state of sys.modules > for reasons that are now somewhat unclear, and still sys.modules is > apparently left in a bad state. > > > > When implementing PEP 615, I ran into similar issues and found it very > difficult to get two independent instances of the same module – one with > the C extension blocked and one with it intact. I ended up manually > importing the C and Python extensions and grafting them onto two "fresh" > imports with nothing blocked. > > When I've had to deal with similar issues in the past, I've given up > on messing with sys.modules and just had one test spawn a subprocess > to do the import+run the actual tests. It's a big hammer, but the nice > thing about big hammers is that there's no subtle issues, either they > smash the thing or they don't. > > But, I don't know how awkward that would be to fit into Python's > unittest system, if you have lots of tests you need to run this way. > > -n > > -- > Nathaniel J. Smith -- https://vorpus.org > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/SDSODK5ZSJUSGDFVFOAESHYLPPFANNWD/ > Code of Conduct: http://python.org/psf/codeofconduct/ > -- --Guido van Rossum (python.org/~guido) *Pronouns: he/him **(why is my pronoun here?)* <http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/>
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