Improving DLL error messages

[marcusva]

Originally reported by: Roger Flores (Bitbucket: rallant92, GitHub: rallant92)

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I installed the 64 bit sdl2 DLLs for my Win 7 x64 OS. Running (draw.py) reported

ImportError: could not load any library for SDL2

After some tracking, I figured out the Python was 32 bit, which can't use 64 bit libs. Specifically, exc at dll.py:57 is "[Error 193] %1 is not a valid Win32 application", raised from CDLL().

The import feedback could be more helpful. Mentioning that a dll file was found but not usable/suitable makes it clear that path issues aren't the source of the problem. So change dll.py:61 to
raise RuntimeError("found %s but it's not usable for the libary %s" % (foundlibs, libinfo))

dll.py:50 could become:
raise RuntimeError("searched %s but could not find any library for %s" % (path, libinfo))

It would also help to mention PYSDL2_DLL_PATH when there's a problem and it's unset so that people know about it.
dll.py:101:
if os.getenv("PYSDL2_DLL_PATH") == None:
exc = exc.message + " (and PYSDL2_DLL_PATH is unset)";

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• Bitbucket: https://bitbucket.org/marcusva/py-sdl2/issue/14

[marcusva]

Original comment by Marcus von Appen (Bitbucket: marcusva, GitHub: marcusva):

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• fixed issue Improving DLL error messages #14: DLL error messages on import should be improved now