Cannot start vspreview

[EleonoreMizo]

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I cannot start VS Preview (Win 7 64 bits). README.md says that only Python 3.8 is required but the warning from the log tells something different and I don’t know if this is the cause of the problem:

2021-10-14 11:16:54.407: WARNING: VSPreview is not tested on Python versions prior to 3.9, but you have 3.8.0 final. Use at your own risk.
2021-10-14 11:16:54.422: DEBUG: Reading QSS file in: :qdarkstyle\dark\style.qss
2021-10-14 11:16:54.422: INFO: QSS file sucessfuly loaded.
2021-10-14 11:16:54.423: DEBUG: Checking patches for being applied.
2021-10-14 11:16:54.423: INFO: Found version patches to be applied.
2021-10-14 11:16:54.423: INFO: Found application patches to be applied.
Traceback (most recent call last):
  File "C:\Program Files\Vapoursynth Preview\run.py", line 4, in <module>
    main()
  File "C:\Program Files\Vapoursynth Preview\vspreview\main.py", line 843, in main
    main_window = MainWindow()
  File "C:\Program Files\Vapoursynth Preview\vspreview\core\bases.py", line 24, in __call__
    cls.instance = super().__call__(*args, **kwargs)
  File "C:\Program Files\Vapoursynth Preview\vspreview\core\better_abc.py", line 25, in __call__
    instance = NativeABCMeta.__call__(cls, *args, **kwargs)
  File "C:\Program Files\Vapoursynth Preview\vspreview\main.py", line 413, in __init__
    self.toolbars = Toolbars(self)
  File "C:\Program Files\Vapoursynth Preview\vspreview\core\bases.py", line 24, in __call__
    cls.instance = super().__call__(*args, **kwargs)
  File "C:\Program Files\Vapoursynth Preview\vspreview\core\better_abc.py", line 25, in __call__
    instance = NativeABCMeta.__call__(cls, *args, **kwargs)
  File "C:\Program Files\Vapoursynth Preview\vspreview\main.py", line 280, in __init__
    self.pipette   =   PipetteToolbar(main_window)
  File "C:\Program Files\Vapoursynth Preview\vspreview\core\better_abc.py", line 25, in __call__
    instance = NativeABCMeta.__call__(cls, *args, **kwargs)
  File "C:\Program Files\Vapoursynth Preview\vspreview\toolbars\pipette.py", line 46, in __init__
    self.outputs = WeakKeyDictionary[Output, vs.VideoNode]()
TypeError: 'ABCMeta' object is not subscriptable

[Endilll]

Thank you for pointing out to stale readme. It says the same as warnings now. Can you upgrade to 3.9 and try again?

[DJATOM]

3.8 is the latest win7 supported version. Maybe its possible to compile 3.9 for win7, but I never tried.

[EleonoreMizo]

Indeed sorry I haven’t any Win 10 rig here so I cannot install Python 3.9 to test.

[Ichunjo]

From this thread , it seems that you can’t add type annotations to abstract base classes in collections.abc. WeakKeyDictionary inherits from collections.abc.MutableMapping so that’s why it doesn’t work in Python 3.8.

https://github.com/Endilll/vapoursynth-preview/blob/4c2c056eec82a29e68ad2b79e88e30ec52ee0a33/vspreview/toolbars/pipette.py#L46

Quick and dirty fix is just removing the annotations of it like this self.outputs = WeakKeyDictionary()

@EleonoreMizo Minor, but you should update to the latest update of 3.8. Friends have a lot of weird issues with 3.8.0 and none with 3.8.10. 3.8.11 and 3.8.12 are just security updates and you can probably skip them. 3.8.10 should be good enough.

[EleonoreMizo]

Thanks for the tip. Unfortunately this leads to other errors, so I guess it’s probably a dead end without Python 3.9.

[Ichunjo]

It worked fine for me using 3.8.10. It was on Windows Server 2019 though.