Pass numpy's include dir to Cmake from Setuptools - c++

Question

I have a C++ library which I have successfully exposed to python using Pybind11.
In the CmakeLists.txt file, I have added the numpy include like this:
include_directories("C:\\Python37\\Lib\\site-packages\\numpy\\core\\include")
This works, but is undesirable. I would like to pass the numpy include directory from my setup.py file.
My setup.py file looks very much like this one:
import os
import re
import sys
import sysconfig
import platform
import subprocess
from distutils.version import LooseVersion
from setuptools import setup, Extension
from setuptools.command.build_ext import build_ext
class CMakeExtension(Extension):
def __init__(self, name, sourcedir=''):
Extension.__init__(self, name, sources=[])
self.sourcedir = os.path.abspath(sourcedir)
class CMakeBuild(build_ext):
def run(self):
try:
out = subprocess.check_output(['cmake', '--version'])
except OSError:
raise RuntimeError(
"CMake must be installed to build the following extensions: " +
", ".join(e.name for e in self.extensions))
if platform.system() == "Windows":
cmake_version = LooseVersion(re.search(r'version\s*([\d.]+)',
out.decode()).group(1))
if cmake_version < '3.1.0':
raise RuntimeError("CMake >= 3.1.0 is required on Windows")
for ext in self.extensions:
self.build_extension(ext)
def build_extension(self, ext):
extdir = os.path.abspath(
os.path.dirname(self.get_ext_fullpath(ext.name)))
cmake_args = ['-DCMAKE_LIBRARY_OUTPUT_DIRECTORY=' + extdir,
'-DPYTHON_EXECUTABLE=' + sys.executable]
cfg = 'Debug' if self.debug else 'Release'
build_args = ['--config', cfg]
if platform.system() == "Windows":
cmake_args += ['-DCMAKE_LIBRARY_OUTPUT_DIRECTORY_{}={}'.format(
cfg.upper(),
extdir)]
if sys.maxsize > 2**32:
cmake_args += ['-A', 'x64']
build_args += ['--', '/m']
else:
cmake_args += ['-DCMAKE_BUILD_TYPE=' + cfg]
build_args += ['--', '-j2']
env = os.environ.copy()
env['CXXFLAGS'] = '{} -DVERSION_INFO=\\"{}\\"'.format(
env.get('CXXFLAGS', ''),
self.distribution.get_version())
if not os.path.exists(self.build_temp):
os.makedirs(self.build_temp)
subprocess.check_call(['cmake', ext.sourcedir] + cmake_args,
cwd=self.build_temp, env=env)
subprocess.check_call(['cmake', '--build', '.'] + build_args,
cwd=self.build_temp)
print() # Add an empty line for cleaner output
setup(
name='python_cpp_example',
version='0.1',
author='Benjamin Jack',
author_email='benjamin.r.jack#gmail.com',
description='A hybrid Python/C++ test project',
long_description='',
# add extension module
ext_modules=[CMakeExtension('python_cpp_example')],
# add custom build_ext command
cmdclass=dict(build_ext=CMakeBuild),
zip_safe=False,
)
After having a look at some SO questions like this, I know that you can get the numpy include directory with numpy.get_include().
However, adding the include directory to the path inside the function build_extension with this line ext.include_dirs.append(numpy.get_include()) seems to have no effect.
I'd like to know how to pass the include directory properly.

Answer 1

Is your cmake build using the wrong numpy path or not finding numpy at all? If it's the wrong path, you could try prepending instead of appending numpy.get_include():
ext.include_dirs.insert(0,numpy.get_include())