'syncplay.vendor.Qt' has no attribute 'QtGui'

[Zahrun]

Describe the bug
Syncplay won’t start.

Traceback (most recent call last):
  File "/usr/bin/syncplay", line 19, in <module>
    ep_client.main()
  File "/usr/lib/syncplay/syncplay/ep_client.py", line 8, in main
    SyncplayClientManager().run()
  File "/usr/lib/syncplay/syncplay/clientManager.py", line 9, in run
    config = ConfigurationGetter().getConfiguration()
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/syncplay/syncplay/ui/ConfigurationGetter.py", line 528, in getConfiguration
    from syncplay.vendor.Qt import QtWidgets, IsPySide, IsPySide2, IsPySide6, QtGui
  File "/usr/lib/syncplay/syncplay/vendor/Qt.py", line 2029, in <module>
    _install()
  File "/usr/lib/syncplay/syncplay/vendor/Qt.py", line 2007, in _install
    our_submodule = getattr(Qt, name)
                    ^^^^^^^^^^^^^^^^^
AttributeError: partially initialized module 'syncplay.vendor.Qt' has no attribute 'QtGui' (most likely due to a circular import)

To Reproduce
Steps to reproduce the behavior:

1. sudo apt install ./syncplay_1.7.4.deb
2. syncplay
3. See error

Expected behavior
Syncplay starts.

Version and platform:

• OS: Tuxedo OS
• Syncplay version and build type: Syncplay 1.7.4 deb
• Media player and version: VLC 3.0.20 amd64

Additional context
Tuxedo OS has KDE Plasma 6.3.2 and QT 6.8.2 on an Ubuntu noble base.

[Et0h]

I'm not a Linux guy, but my guess is that you need to install PySide2/PySide6 (depending on Python version). See requirements in https://syncplay.pl/guide/install/

[Zahrun]

Thank you for your reply.
python3-pyside2.qtwidgets was already installed on my system.
I fixed the issue by installing python3-pyside6.qtwidgets.

Should python3-pyside6.qtwidgets be made a dependency of the deb?

I see that currently the deb has:

Depends: python3 (>= 3.6), python3-pyside2.qtwidgets | python3-pyside6.qtwidgets, python3-pyside2.qtcore | python3-pyside6.qtcore, python3-twisted (>= 16.4.0), python3-certifi, python3-pem, mpv (>= 0.23) | vlc (>= 2.2.1)

So it will install if either pyside2 or pyside6 is installed.

In which scenario will pyside2 not be sufficient?

[Zahrun]

From what I read online, PySide2 is for Qt5 and PySide6 is for Qt6.
So maybe I would recommend adding a note on the Installation guide https://syncplay.pl/guide/install/
Where it reads

Additional requirements for GUI:

    PySide2 (>=5.11.0 except for 5.15.0) (on Debian based distros use python3-pyside2.qtwidgets) – Syncplay supports PySide6 for those on Python >=3.12

Could be added PySide6 is required for compatibility with systems using Qt6 such as KDE Plasma 6

[daniel-123]

@Zahrun this is actually a known problem. The package requires both qtwidgets and qtcore from the same pyside version. So if you have one of them from pyside6 and one from pyside2, it will cause issues. Yea, Syncplay probably should be a bit smarter about detecting this, providing appropriate error message or something along those lines. Or at very least test which version of pySide is complete before trying to run with it.

There is no way to set up this exact logic in the deb package requirement without using a secondary package just for purpose of managing the dependencies. I do actually wonder what would be the best solution here, with options being:

• Revert to previous behavior of depending on pySide2. It is still widely supported for now, even if in general this will result in pulling in Qt5 dependencies people otherwise might not be using by now.
• Make two separate deb packages, one "modern" with pySide6 as dependency and one "legacy" that needs pySide2. It is a bit of extra work, but probably the most appropriate transition path.
• Straight up require pySide6 across the board, which is not a good idea for now because pySide6 is very recent to Debian-derivative distros and to my knowledge not available in any of the latest LTS releases.

All that said, apt install syncplay should have worked just fine. Is there any specific reason you choose to install deb from our repo manually? I'm quite interested if we should modify our guides or links so that they lead people more strongly towards OS repositories.

[Zahrun]

@daniel-123 actually I wanted the latest version to try and benefit from the new features and bug fixes. The syncplay version which is available in the Ubuntu noble repo is 1.7.0 which is 2 years old at this point.

I used to rely on AppImage releases up to 1.7.0 which was the latest AppImage release.

I agree with you that requiring straight up pySide6 is too early, since debian stable and Ubuntu LTS lack those packages.
I would be favourable to the route of having two separate deb packages, but I understand that would be more work.
Maybe adding some relevant information in the Installation guide https://syncplay.pl/guide/install/ would suffice. I went and read that page when I faced the issue, but the sentence Syncplay supports PySide6 for those on Python >=3.12 didn’t attract my attention much.