The core of pytorch does not depend on Python. A CMake-based build system compiles the C++ source code into a shared object, libtorch.so.
You can use a python script/module located in tools package to build libtorch :: cd <pytorch_root>
# Make a new folder to build in to avoid polluting the source directories mkdir build_libtorch && cd build_libtorch
# You might need to export some required environment variables here. Normally setup.py sets good default env variables, but you'll have to do that manually. python ../tools/build_libtorch.py
Alternatively, you can call setup.py normally and then copy the built cpp libraries. This method may have side effects to your active Python installation. :: cd <pytorch_root> python setup.py build
ls torch/lib/tmp_install # output is produced here ls torch/lib/tmp_install/lib/libtorch.so # of particular interest
To produce libtorch.a rather than libtorch.so, set the environment variable BUILD_SHARED_LIBS=OFF.
To use ninja rather than make, set CMAKE_GENERATOR="-GNinja" CMAKE_INSTALL="ninja install".
Note that we are working on eliminating tools/build_pytorch_libs.sh in favor of a unified cmake build.