Moore, Paul writes:
On point 3a, sys.extinstallpath should be set for all platforms, but I have to admit that I don't know what to do for non-Windows platforms. The best I can suggest is that we do something like
if os.sep == '/': sys.extinstallpath = os.path.join(sys.prefix, "lib", "python" + sys.version[:3], "site-packages") else: sys.extinstallpath = os.path.join(sys.prefix, "lib", "site-packages")
There's one aspect that doesn't appear to have been addressed for Unix: there are two reasonable values for extinstallpath. In multi-architecture installations, where the Python portions of the library are shared among architectures, there are two site-packages directories:
When $prefix and $exec_prefix are the same, this isn't an issue, but for this is a problem for multi-platform installations.