Release 6.2 does not work under Unbuntu 18.04 anymore

[dewagter]

When installing paparazzi release 6.2 on a fresh ubuntu 18.04, it does not even start paparazzi center

• missing lxml (sudo apt-get install python3-lxml)
• missing numpy (sudo pip3 install numpy)
• missing PyQt5 (sudo apt-get install python3-pyqt5)
• missing dataclasses (sudo pip3 install dataclasses)
• syntax error: supervision/python/paparazzicenter.py utils.py line 21: def remove_prefix(string: str, prefix: str, ,/) -> str
  does not understand this /) -> removed the ", /"
• missing future annotations: (tried: git clone -b legacy_py3.6 http://github.com/QUVA-Lab/e2cnn.git && cd e2cnn && sudo python3 setup.py install, but required python3.8)
• unable to fix: recommend minimum python3.7
• sudo add-apt-repository ppa:deadsnakes/ppa
• sudo apt-get update
• apt list | grep python3.8
• sudo apt-get install python3.8
• sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.6 1
• sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.8 2
• sudo update-alternatives --config python3 (and then type 2)
• check python3 -V
• sudo apt-get remove gpsd (gives errors with pkg)
• missing PyQt5.Widget etc....

Tried removing old pythons

• sudo apt purge python2.7-minimal
• sudo apt purge python3.6
• sudo ln -s /usr/bin/python2 /usr/bin/python
• sudo apt install -y python3-pip
• sudo ln -s /usr/bin/pip3 /usr/bin/pip
• sudo apt autoremove
• ls -al /usr/bin | grep python

[Fabien-B]

Ubuntu 18.04 is being rolled out of support in 2 months.
I think it's not worth fixing, knowing that you can use the old paparazzi center.
Just launch it with ./paparazzi -legacy.

I don't think we should restrains ourself to use the "new" nice things to keep it compatible with the old end of life distributions.
The shift to Qt is due to the end of support of Gtk2 and ocaml-gtk bindings in Ubuntu 20.04 and later.
We choosed to provide no support for the new GCS and paparazzi center in 18.04, as the old tools are working fine in this version.

[gautierhattenberger]

The paparazzi-dev package have not been updated in include the python libraries for the new pprz center. I also don't think it is worthy to change that. We might test for the ubuntu version to decide if the legacy version should be used by default or not.

[dewagter]

Updated documentation so people know what to do and the start.py still works like before.

[dewagter]

In summary: solving the python issues seems very challenging but as suggested by @gautierhattenberger the legacy mode still works great. This is now reflected in the documentation so this issue is resolved.