This folder sets up a explicit_python target, which lets you link against an explicitly specified
(Windows) Python version. FindPython is generally not suitable for what we do, since it picks an
arbitrary version on your system, which may not even be the right architecture, and it picks a host
version if cross compiling. This target also adds install rules for the .dlls, .pyds, and
.zips which are needed at runtime when running an embedded interpreter.
The simplest way to use this is just to set EXPLICIT_PYTHON_VERSION to the relevant version, and
EXPLICIT_PYTHON_ARCH to one of win32 or amd64, before including this folder in CMake.
This requires Python with requests to be on your PATH, and, if not running on Windows,
msiextract (typically part of an msitools package).
When setting the above variables, CMake will automatically run download.py. You can instead run it
yourself, and point EXPLICIT_PYTHON_DIR at the folder you downloaded. You can also set this as an
environment variable, which can be useful if caching it in a container.
The final way to use this is to point EXPLICIT_PYTHON_DIR at a standard Windows Python install.
This of course requires you install the development version. Windows installs do not normally come
with a python3<version>.zip standard library zip. This is not required to compile, and won't throw
an error, but is needed at runtime. There are three ways you can get it:
- Just zip the
Libup folder, and rename it. - Download the python embeddable package for the same version, and copy the zip from there. This
version contains precompiled bytecode instead of raw source files. This is what the
download.pyscript does. - Create your own compiled zip using
zipfile.PyZipFile. You have to make sure to do this with the exact same Python version.