On Tue, 7 May 2019 at 21:53, Chris Angelico <ros...@gmail.com> wrote: > > I've been building Python 3.8 pre-alphas and alphas for a while now, > and ran into a weird problem. Not sure if this is significant or not, > and hoping to get other people's views. > > It seems that the value of sys.implementation.cache_tag changed from > "cpython-38m" to just "cpython-38" at some point. That means that a > statement like "import lzo" will no longer find a file called > "lzo.cpython-38m-x86_64-linux-gnu.so", which I had had prior to the > change. The trouble is, pip *did* recognize that file, and said that > the python-lzo package was still installed. > > Solution: "pip uninstall python-lzo" and then reinstall it. Now it's > created "lzo.cpython-38-x86_64-linux-gnu.so" and all is well. > > Does anyone else know about how pip detects existing files, and > whether it could be brought more in sync with the import machinery?
I don't know if this is what you were after, but pip decides if a project FOO is installed by looking for the FOO-X.Y.Z.dist-info directory in site-packages. The RECORD file in that directory contains a list of all files installed when the package was originally installed (that's what pip uses to decide what to uninstall). Paul -- https://mail.python.org/mailman/listinfo/python-list
