visidata: add runtime dependency of clipboard commands

[AndrewKvalheim]

Description of changes

VisiData’s system clipboard commands (e.g. Edit → Copy → to system clipboard) currently fail with:

FileNotFoundError: [Errno 2] No such file or directory: 'xclip'

This can be corrected in the user’s configuration, and for e.g. Wayland you might prefer to specify different commands anyway—

{
  home.file.".visidatarc".text = ''
    options.clipboard_copy_cmd = '${wl-clipboard}/bin/wl-copy'
    options.clipboard_paste_cmd = '${wl-clipboard}/bin/wl-paste --no-newline'
  '';
}

—but it would be nice if the defaults worked out of the box.

https://github.com/saulpw/visidata/blob/v2.8/visidata/clipboard.py#L18-L19

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • package tests
• Tested compilation of all packages that depend on this change using nixpkgs-review rev visidata/xclip
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 22.11 Release Notes (or backporting 22.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Release notes changes) Ran nixos/doc/manual/md-to-db.sh to update generated release notes
• Fits CONTRIBUTING.md.

[markus1189]

Using xclip as the default command assumes that stdenv.isLinux = true implies the environment is also using X11. With is not necessarily true, it might be Wayland. I don't know if xclip works in that case at all, does somebody know it?

[AndrewKvalheim]

Yep, it’s naive, but that’s the behavior of the application. For what it’s worth, xclip does appear to work in my Wayland GNOME environment.

The other case worth considering is non-graphical environments, and whether the extra dependency (or visidata.override { xclip = null; }) is unacceptably burdensome there.

If we wanted to get into more elaborate packaging, pass might be a useful example/precedent.

[markus1189]

What do you think about having something like:

lib.optionals withXclip [ xclip ];

instead? And then we could default withXclip to stdenv.isLinux

[AndrewKvalheim]

That sounds good, thanks. I’m still new to this though so don’t give my input too much weight. :)

[RamKromberg]

Partially off-topic, if anyone runs into copy-pasting type issues with visidata, be sure to update xclip before assuming it's a visidata bug. Upstream stopped doing point releases so the version in nixpkgs is 8 years behind:
https://github.com/NixOS/nixpkgs/blob/master/pkgs/tools/misc/xclip/default.nix
https://github.com/astrand/xclip/commits/master