Get Python's LIB path

Question

I can see that INCLUDE path is sysconfig.get_path('include').

But I don't see any similar value for LIB.

NumPy outright hardcodes it as os.path.join(sys.prefix, "libs") in Windows and get_config_var('LIBDIR') (not documented and missing in Windows) otherwise.

Is there a more supported way?

Answer 1

Since it's not a part of any official spec/doc, and, as shown by another answer, there are cases when none of appropriate variables from sysconfig/distutils.sysconfig .get_config_var() are set,

the only way to reliably get it in all cases, exactly as a build would (e.g. even for a Python in the sourcetree) is to delegate to the reference implementation.

In distutils, the logic that sets the library path for a compiler is located in distutils.commands.build_ext.finalize_options(). So, this code would get it with no side effects on the build:

import distutils.command.build_ext    #imports distutils.core, too
d = distutils.core.Distribution()
b = distutils.command.build_ext.build_ext(d)  #or `d.get_command_class('build_ext')(d)',
                                              # then it's enough to import distutils.core
b.finalize_options()
print b.library_dirs

Note that:

• Not all locations in the resulting list necessarily exist.
• If your setup.py is setuptools-based, use setuptools.Distribution and setuptools.command.build_ext instead, correspondingly.
• If you pass any values to setup() that affect the result, you must pass them to Distribution here, too.

---

Since there are no guarantees that the set of the additional values you need to pass will stay the same, and the value is only needed when building an extension,

• it seems like you aren't really supposed to get this value independently at all:
  • If you're using another build facility, you should rather subclass build_ext and get the value from the base method during the build.