Hi Jeff, thank you for your expert and thorough response! You make a good point that users usually pipe the output of a prettier tool to a pager themselves. In the case of delta, delta can be configured to selectively pipe to a pager itself, so delta's docs doesn't tell users to pipe: `core.pager = delta` (source: https://dandavison.github.io/delta/configuration.html) However, for diff-so-fancy, it might not work cleanly because users are told to explicitly pipe it to a pager. `core.pager "diff-so-fancy | less --tabs=4 -RFX"` (source: https://github.com/so-fancy/diff-so-fancy#with-git). I haven't looked at other tools but it's clear this approach is not guaranteed to work for all configurations so I should look into something else. Jeff, would you be so kind as to elaborate more on the interactive.diffFilter approach? My understanding is that interactive.diffFilter is only used for git add -p or git reset -p. However, the limitation for my use case is I need to use the pager for git log and git show so that won't work. So then, you are suggesting that I ask my users to opt in by setting an arbitrary git config like fzf.pager and then read out the pager from that git var? On Tue, Aug 15, 2023 at 7:57 PM Jeff King <peff@xxxxxxxx> wrote: > > On Tue, Aug 15, 2023 at 05:09:13PM -0700, Patrick wrote: > > > I noticed there is no option I can pass to git to use the pager set in > > my gitconfig even when piping to non-TTY. Is there a workaround? If > > not, may I request this as a new feature? > > I don't think there is a workaround. We have "git --paginate", but it > really means "paginate this command using the default rules, even if it > is not a command that is usually paginated". > > Looking at the code in setup_pager(), I think the check for "is stdout a > tty" is fed directly into the decision of whether to use a pager. > There's no way to override it within Git. You'd have to trick Git by > opening a pty in the calling program and pumping the data through it > (which is what our test suite does; see t/test-terminal.perl). > > So I think it would need a new option. But... > > > Use case: integrate tools like Delta or diff-so-fancy when building > > wrappers around git commands. See > > https://github.com/dandavison/delta/discussions/840 and > > https://github.com/PatrickF1/fzf.fish/discussions/202 for examples. > > I'm not quite sure that's what you want. When a user configures a custom > pager using a prettifier tool like that, they usually further pipe the > output to a pager like "less". E.g., I have: > > [pager] > log = diff-highlight | less > > in my config. If you are trying to save output that looks like what the > user would see on their tty, you want the first half of that pipeline > (the diff-highlight here), but not the second (less). Of course it > mostly works because less is smart enough to behave like a noop "cat" > when stdout isn't a tty. So it might be OK in practice. > > I think your script might be better off doing the piping itself. In > theory you could ask Git what the configured pager is and the run it > yourself, but: > > 1. You can use "git var GIT_PAGER" to get the default pager, but not > command-specific ones. So you'd have to check "git config > pager.log", etc, yourself, which means reimplementing some of Git's > logic. > > 2. You'd get a string like "diff-highlight | less", and then you'd > have to decide whether to parse off the "| less" part yourself, > which is obviously error-prone since the string can be an > arbitrarily complex shell expression. > > When we were faced with a similar situation within Git, we ended up > adding a new config option: interactive.diffFilter. This is used by "add > -p", etc, to filter diffs that are shown to the user. It does mean the > user has to repeat themselves (I have to set it to "diff-highlight" > separately from my settings for pager.log, pager.diff, etc). But it's > unambiguous, and it gives the user the flexibility of configuring > various outputs differently if they choose. > > So depending on what your script does, you could use a similar config > option. Or even just use interactive.diffFilter if your use case is > conceptually the same. > > -Peff
