I'm working on a C++/Python project with the following structure:
foo
├── CMakeLists.txt
├── include
├── source
└── python
├── foo
│ ├── _foo_py.py
│ └── __init__.py
├── setup.py
└── source
├── CMakeLists.txt
└── _foo_cpp.cpp
foo/source and foo/include contain C++ source files and foo/python/source/_foo_cpp.cpp contains pybind11 wrapper code for this C++ code. Running setup.py is supposed to build the C++ code (by running CMake), create a _foo_cpp Python module in the form of a shared object and integrate it with the Python code in _foo_py.py. I.e. I want to be able to simply call python setup.py install from foo/python to install the foo module to my system. I'm currently using a CMake extension class in setup.py to make this work:
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:
subprocess.check_output(['cmake', '--version'])
except OSError:
raise RuntimeError("cmake command must be available")
for ext in self.extensions:
self.build_extension(ext)
def build_extension(self, ext):
if not os.path.exists(self.build_temp):
os.makedirs(self.build_temp)
self._setup(ext)
self._build(ext)
def _setup(self, ext):
cmake_cmd = [
'cmake',
ext.sourcedir,
]
subprocess.check_call(cmake_cmd, cwd=self.build_temp)
def _build(self, ext):
cmake_build_cmd = [
'cmake',
'--build', '.',
]
subprocess.check_call(cmake_build_cmd, cwd=self.build_temp)
The problem arises when I try to directly call pip in foo/python, e.g. like this:
pip wheel -w wheelhouse --no-deps .
It seems that before running the code in setup.py, pip copies the content of the working directory into a temporary directory. This obviously doesn't include the C++ code and the top-level CMakeLists.txt. That in turn causes CMakeBuild._setup to fail because there is seemingly no way to obtain a path to the foo root directory from inside setup.py after it has been copied to another location by pip.
Is there anything I can do to make this setup work with both python and pip? I have seen some approaches that first run cmake to generate a setup.py from a setup.py.in to inject package version, root directory path etc. but I would like to avoid this and have setup.py call cmake instead of the other way around.
