Broken with Python 3.8+ on Windows

[oddMLan]

Apparently the Python Software Foundation in a moment of pure brilliance decided to break DLL resolution in Python 3.8+
"it's not a bug; it's a feature": https://bugs.python.org/issue43173

In 3.8+, the search path for the dependent DLLs of a normally imported extension module includes the following directories:

• the loaded extension module's directory
• the application directory (e.g. that of python.exe)
• the user DLL search directories that get added by
  SetDllDirectory() and AddDllDirectory(), such as with
  os.add_dll_directory()
• %SystemRoot%\System32

If possible, the simplest approach is to put dependent DLLs in the same directory as the extension module.

More details:
#589 (comment)

[liZe]

Hello!

Well… It’s probably time to follow what the Python devs say:

If your application relies on [DLL loading], you should check for add_dll_directory() and if it exists, use it to add your DLLs directory while loading your library.

[liZe]

This bug is now closed 🚀.

We’ve added a WEASYPRINT_DLL_DIRECTORIES environment variable to list folders where the DLL files can be found. Python 3.8+ will look there to find the libraries. The default value is the default folder of the GTK3 installer.

Feedback is welcome!