allow for bookdown hacking?

[maelle]

alternative title: make downlit_html_path() more flexible. :-)

Context: I am working on a bookdown gitbook and was trying to find a hack to use downlit before it gets really supported (so patient 🙈 ). I set bookdown's highlight parameter to NULL then I use downlit::downlit_html_path() on all resulting HTML but the HTML nodes don't have the classes downlit would expect e.g.

<pre class="r"><code>summary(cars)</code></pre>
<pre><code>##      speed           dist       
##  Min.   : 4.0   Min.   :  2.00  
##  1st Qu.:12.0   1st Qu.: 26.00  
##  Median :15.0   Median : 36.00  
##  Mean   :15.4   Mean   : 42.98  
##  3rd Qu.:19.0   3rd Qu.: 56.00  
##  Max.   :25.0   Max.   :120.00</code></pre>

Therefore I tweaked the xpath and now I only need to add a CSS and my gitbook will get autolinking today.

I reckon tweaking the package out of impatience is maybe not a good idea.

[maelle]

My bookdown _output.yml contains

bookdown::gitbook:
  css: style.css
  highlight: NULL

where style.css contains styling for Chroma classes.

Then I run

bookdown::render_book(".")
htmls <- file.path(
  getwd(), 
  dir("docs", full.names = TRUE)
)
htmls <- htmls[grepl("\\.html$", htmls)]
purrr::walk2(
  htmls, htmls,
  downlit::downlit_html_path,
  classes = downlit::classes_chroma()
  )

And the gitbook looks really nice.

But maybe I'll have to wait for actual downlit support in html_document() :-)

[maelle]

I am now questioning my approach after seeing the use of a knitr hook in distill.

At the moment I use tweaks of downlit and the tweaked build workflow (knitting, then highlighting all HTML) described above.

Maybe with a hook I could do without asking for tweaks of downlit and instead my work would be a) writing the hook, saving it in a chunk in an R file b) referring to it in before_chapter_script but adding logic to only execute the chunk for the gitbook output and I only know knitr::is_latex_output() for PDF vs HTML, not useful if there's an EPUB too.) 🤔 I could try that next week... (especially as it'd mean I get Pandoc highlighting for other languages)

[maelle]

I take it back, with a hook there'd be no autolinking of inline code.

[hadley]

Thanks!

[cderv]

with a hook there'd be no autolinking of inline code.

@maelle, out of curiosity, you mean with a source hook or any hooks?
Because there is a separate hook for inline R code - It is not the source hook which is used for inline R code.

[hadley]

@cderv inline linking applies to `foo()` not `R foo()`

[cderv]

Oh I see. 😄 Thanks ! That is obvious when you write it. 😅

[hadley]

It's only obvious to me because I tried using the inline code hook and I couldn't figure out why it didn't work 😆