FR: Ability to specify pager by diff-tool

[sfleiter]

Is your feature request related to a problem? Please describe.
Depending on the kind of diff I want to review I prefer either to view changes with difft aka difftastic or diffnav

Describe the solution you'd like

• I want to be able to select the diff formater via --tool X without any need to change configuration or provide further parameters. For that the following is necessary
  • Setting the pager in the diff tool configuration since there are diff tools that can only work as a pager
  • Configure the output format that is send into the pager like with the --git parameter
  • (I wonder why diff formatting is configured via merge-tools.<name> but that is a different story I guess)

Describe alternatives you've considered
Overriding the pager and diff format for diffnav globally as described in docs

[ui]
pager = "diffnav"
diff-formatter = ":git"

When wanting to use difft, which is supposed to be my default, I have to run jj SOME_COMMAND --no-pager --tool difft instead of just jj SOME_COMMAND.
Also how much globally setting pager is a workaround is probably well documented in the scope tables section

Second alternative is this alias which is ugly since it destroys shell tab completion. I can use diffnav by calling jj diffnav SOME_COMMAND

[aliases]
diffnav = [  "util",  "exec",  "--",  "bash",  "-c",  """
jj "$@" --git | diffnav
""", "jj" ]

Additional context
I have probably wasted too much time to find these alternative options.
I am going to use the alias configuration for now.

[yuja]

I think the requested feature is too specific. One alternative idea is to pass JJ_COMMAND_ARGS=diff --tool whatever ... to the pager, so the wrapper script can choose diffnav or less by parsing the passed environment variable.

BTW, you can use --config ui.pager=... in [aliases] to override the default pager.