Allow to skip formatting code in specific cells

[hfrick]

Description

I'm preparing slides via quarto and generally use air to format my code. For some of the code cells, I'd like to skip the formatting. I can do that with air's # fmt: skip, but then it shows up on the resulting slide. Since these are workshop slides, I'd like to avoid this since it would probably be a distraction to learners. Is there a way to skip formatting specific cells without it showing on the slide? Would something like #| format: skip be possible?

I have seen #12082 but I think it's related but different.

[mcanouil]

Formatters are currently handled on the IDE side with for instance the VSCode/Positron extension.
That's not something controlled by Quarto CLI.

Note that (minus the few known issues), you can format your code at cell level.

The repository of the extension and where the integration with formatters is done is: https://github.com/quarto-dev/quarto

[cscheid]

Context

Quarto has some precedent for doing similar things, specifically with the echo: fenced value in metadata. Consider:

---
format: html
---

## Code cell 1
```{r}
#| echo: fenced
#| error: true
# fmt: skip
cat("with echo")
```

## Code cell 2

```{r}
#| echo: false
cat("without echo")
```

output

Note how echo: fenced doesn't itself show in that output.

With this said, the code that implements this is pretty hacky and I wouldn't want to try to make it more general without rethinking it all for a bit. (In other words, we won't be able to do this for conf)

Workaround

On the other hand, you could do this removal yourself with a Lua filter that removes the comment from the CodeBlock node:

function CodeBlock(code)
  if not code.classes:includes("cell-code") then
    return nil
  end
  code.text = code.text:gsub("# fmt: skip\n", "")
  return code
end

Then, add

filters:
  - remove_fmt.lua

to your document.

Result

[hfrick]

Thanks for this, Carlos! I think this would be a neat feature in the future. I'll make a note for us to look into a Lua filter in the meantime (after conf 🤪 ).

[cderv]

Is there a way to skip formatting specific cells without it showing on the slide? Would something like #| format: skip be possible?

I wonder how air is called on R cells inside the Quarto document. 🤔 Maybe this is a feature request for air in combination with Quarto to allow #| fmt: skip also to avoid formatting some code, in addtion of # fmt: skip

It could be a question to ask on https://github.com/posit-dev/air too

[mcanouil]

In VSCode/Positron it's possible to implement logic to skip formatting similar to the approach of skipping the formatting of options in Python code cell (ongoing PR).

[DavisVaughan]

I think this is more of a Quarto feature request that would be useful across all languages Quarto supports.

Like

```{python}
#| skip-formatting = true

```

as Quarto parses the document it would also parse these cell comments, and this cell comment would be a signal that Quarto should not include this particular cell in the underlying virtual doc that the python formatter is actually run on

[mcanouil]

FYI, the PR I mentioned which exactly does that is quarto-dev/quarto#655.
This PR only excludes #| from being formatted (i.e., # |) for Python code cells.

From there, we can imagine extending it.
Note that Posit Air uses # fmt: skip comment (personal note: I don't like this abbreviated name though).
I think the design would be to have a more general option which takes a string as value which could later eventually be extended, e.g., #| format: skip or #| formatting: skip.

[cderv]

Thanks for the additional information @DavisVaughan. I was missing how the formatting happens. This makes sense.

Thanks for linking @mcanouil - indeed we could do something like this. #| format: false would be another option, as we usually use true / false for opt-in or opt-out.

Note to self: this probably needs to map with tidy option on knitr side for syncing the two feature.

[mcanouil]

Before the choice of the name (basically the design), first we (I) need to add some tests and validate the "skip logic", then we can explore a more broader approach to skip formatting regardless of the language.

[mine-cetinkaya-rundel]

I wonder if we can move this to an issue to track, I would be very interested in a Quarto option that will operate across languages and both at the code cell and the document level. I have Quarto projects where I want air to work on save on all documents except for slides, for example (as slides require a lot more management of the limited screen real estate).

[cscheid]

Yes, let's do that.

[mcanouil]

Now tracked at:

• https://github.com/quarto-dev/quarto-cli/issues/13395