How can you get delta to default to using diff-so-fancy everywhere but also allow side by side once in a while?

[nickjj]

In my shell's rc file I put export DELTA_FEATURES="+diff-so-fancy" and then my git config doesn't need to always supply that flag. This is handy because I sometimes use delta directly with fzf and this strategy works there too. I figured this would be preferred over aliasing delta to delta --diff-so-fancy since shell aliases don't get picked up when using git commands or when calling delta in other scripts.

But now I'd like to sometimes enable side-by-side mode on demand when running various diff related commands.

I thought I could do this, but neither of these work as expected:

# This does set side by side, but it cancels out diff-so-fancy.
DELTA_FEATURES="+side-by-side" git diff

# This applies diff-so-fancy but side-by-side doesn't happen.
DELTA_FEATURES="+diff-so-fancy +side-by-side" git diff

I couldn't find any references in the docs on how to apply more than 1 feature.

If I set --side-by-side directly as a CLI option to Delta or define it in [delta] within my git config then it works but I want to avoid always having that set. But this at least demonstrates the feature can co-exist with diff-so-fancy.

[nickjj]

I managed to get it to work but it feels like I might be doing something wrong.

In my rc file I'm now using export DELTA_FEATURES="diff-so-fancy" with no +.

Then if I call DELTA_FEATURES="diff-so-fancy side-by-side" git diff it works by applying both.

The issue is you have to define both together. It's also possible to do DELTA_FEATURES="${DELTA_FEATURES} side-by-side".

I thought maybe I could have done DELTA_FEATURES="+side-by-side" to say "keep the current value of delta features but also add this new option" to avoid re-defining the entire env var but this results in only applying side-by-side.

Is this a bug or is something not documented?

[dandavison]

Hi @nickjj!

I couldn't find any references in the docs on how to apply more than 1 feature.

This is technically documented here I think: https://dandavison.github.io/delta/features-named-groups-of-settings.html

it should be set to a space-separated string of feature names. If you precede this with a + symbol, then the features are added to those configured elsewhere, instead of replacing them.

And I absolutely agree, toggling them on and off independently via the space-separated-string env var is not a fun experience if done manually. So far my pain with this has led me to write the Python script linked at

https://dandavison.github.io/delta/tips-and-tricks/toggling-delta-features.html

As I say there, I could see perhaps that being moved into Rust, something like

eval "$(delta toggle side-by-side)"

perhaps? Open to design ideas and PR contributions!

[dandavison]

(Another related pain point is that delta has a man-style --help and also the HTML manual at https://dandavison.github.io/delta, and they inevitably have partial overlap; not sure what best to do there.)

[nickjj]

Hi,

Yeah I think adding it to Delta itself would be helpful.

The docs mention:

If you precede this with a + symbol, then the features are added to those configured elsewhere, instead of replacing them

I would have expected this to work where I do export DELTA_FEATURES=+side-by-side since that's in the docs but this didn't work. I am guessing this maybe only works if you have other delta options defined in your git config and it adds to that, not an existing DELTA_FEATURES environment variable?

Maybe that could be the new Delta feature? To modify that behavior from looking at your git config to looking at your git config and also look at an existing DELTA_FEATURES env var variable and if it's populated, then append to it just like you would do it in the shell with DELTA_FEATURES="${DELTA_FEATURES} side-by-side" in terms of the end result. This could avoid needing to modify the current shell with eval to re-export it.