Syntax conflict between knit_expand and Quarto extensions?

[daranzolin]

I'm having difficulty using Quarto extensions within a child document, and I'm wondering if there's a syntax conflict with the curly braces. For example, knit_expand uses "{{i}}" to reference a variable, and Quarto extensions start and end with '{...}' I'll try and spin up a reprex at some point, but the error I'm getting is:

Error: Failed to parse the inline R code: < ...... (Reason: <text>:1:1: unexpected '<'
1: <
    ^)

[cscheid]

We'll unfortunately need a full example before being able to help.

[daranzolin]

Ok, I created a gist here.

The error:

Quitting from lines 8-13 (template.qmd) 
Error: Failed to parse the inline R code: < downloadthis ", "'", path, "'", ' dname=Mtcars label="Download the mtcars data" icon=database-fill-down type=info class=data-button id=mtcars > (Reason: <text>:1:1: unexpected '<'
1: <
    ^)

Execution halted

Edit: 'mtcars.csv' must be in the same project directory, sorry.

Edit2: I've tried using a couple other Quarto extensions within child.qmd and none of them have worked.

[baptiste]

I still don't get what you want to expand in the knit_expand template (maybe nothing in your example?), but as far as the curly-brace convention is concerned, you can simply use different delimiters, e.g

src = knitr::knit_expand("child.qmd", delim = c("<<", ">>"))

Edit: I've forked your gist with an example using different delimiters, and expanding a variable in the template

[daranzolin]

@baptiste that works, thank you!!!! Didn't know about the delim argument. I think it also confirms my initial hunch that knit_expand() and the quarto extension syntax were in conflict.

[mcanouil]

For the sake of clarity, there is no {{ ... }} convention in Quarto.
It's shortcode syntax which is {{< ... >}}.

[cderv]

To complete what @baptiste said, I don't think you need knit_expand() here, as there is nothing to expand.

I don't think we should consider conflict here. It is just that if you need to use knit_expand() with some content that are using the default delimiters as not-delimiter to R code to evaluate, then the delim argument should be used. knitr feature found int the function help page. The issue would be the same with glue package to build some Markdown string for Quarto using brackets.

Regarding your gist, it could be done with knit_child() and without a child.qmd, but I assume this was a minimal reprex of a larger usage.
here is an example where knit_expand is used to replace path in the string to build a shortcode.

path <- fs::path("mtcars", ext = "csv")
src = knitr::knit_expand(
  text = "{{< downloadthis '<< path >>' dname=Mtcars label=\"Download the mtcars data\" icon=database-fill-down type=info class=data-button id=mtcars >}}",
  delim = c("<<", ">>")
)
src
#> [1] "{{< downloadthis 'mtcars.csv' dname=Mtcars label=\"Download the mtcars data\" icon=database-fill-down type=info class=data-button id=mtcars >}}"

^{Created on 2023-02-09 with reprex v2.0.2}

And below is an example to create a function that does output the built string to be include asis by knitr

```{r, include = FALSE}
download_this <- function(path) {
  src <- knitr::knit_expand(
    text = "{{< downloadthis '<< path >>' dname=Mtcars label=\"Download the mtcars data\" icon=database-fill-down type=info class=data-button id=mtcars >}}",
    delim = c("<<", ">>")
  )
  knitr::asis_output(src)
}
```

```{r}
download_this("mtcars.csv")
```

hope it helps understand

[daranzolin]

@cderv thanks, that's also really helpful!