Release knitr 1.34 · yihui/knitr

NEW FEATURES

Added a package option latex.tilde so that users can customize the tilde symbol, e.g., you can set knitr::opts_knit$set(latex.tilde = "\\hlopt{\\scriptsize{\\ensuremath{\\sim}}}"). This is because the default tilde is too high in the PDF output, and it's often more desirable to use a middle tilde instead (thanks, @brry #1992, @jaredlander #492).
For the tikz engine, the class options of the standalone document classs can be specified via the chunk option engine.opts$classoption (thanks, @XiangyunHuang, #1985). The default value is tikz, i.e., \documentclass[tikz]{standalone} is used by default.
Added the ability to pass additional arguments to dvisvgm when using the tikz engine with fig.ext = "svg" by using dvisvgm.opts in engine.opts (thanks, @andrewheiss, #2039). Recent versions of dvisvgm now allow you to embed fonts into SVG files as base64-encoded WOFF files, so tikz chunks can embed fonts using like so: ```{tikz, fig.ext="svg", engine.opts=list(dvisvgm.opts = "--font-format=woff")}.
Added a new targets engine (ropensci/targets#503, @wlandau). Details: https://books.ropensci.org/targets/markdown.html.
The chunk option cache.globals can take values TRUE and FALSE now (in addition to a character vector). When FALSE, it tries to find all symbols in the code chunk, no matter if they are local or global variables. When NULL or TRUE, it tries to find all global variables (thanks, @knokknok, #1898).

An error is now thrown when an inline code result is not coercible to character. This has always been the assumed behavior but it happens to be different in certain formats with unknown automatic coercion. This is now enforced to prevent any unexpected output. An inline code expression must evaluate to a character vector or an object coercible by as.character() (#2006).
The markdown package has been moved from Imports to Suggests in knitr's DESCRIPTION, which means it is no longer a hard dependency but has become a soft dependency of knitr (#1864). One consequence for package developers is that if you use the vignette engines based on markdown (such as knitr::knitr), you will have to explicitly declare the (soft) dependency on markdown, because the implicit dependency through knitr is no longer there.
For R packages that use the knitr::rmarkdown engine to build their vignettes, rmarkdown must be declared as a dependency in the package DESCRIPTION (e.g., in Suggests). Previously, knitr would fall back to using the markdown package to build vignettes if rmarkdown is not declared (#1864, #2020).
write_bib() only uses the first URL if multiple are found in a package (#2028).

The attribute data-external="1" will be added to <iframe>s generated by include_url() to prevent Pandoc from embedding the URL as base64 data (thanks, @IndrajeetPatil, https://stackoverflow.com/q/67477667/559676).
The chunk option strip.white = TRUE used to work only when the chunk option collapse = FALSE. Now the two options are independent, i.e., strip.white also works when collapse = TRUE (thanks, @kbvernon, #2011).
When building R Markdown vignettes but Pandoc is not available, the vignette engine will emit a message instead of a warning before falling back to using the markdown package.
The internal function is_abs_path() has been removed. Users (if any) should use the exported function xfun::is_abs_path() instead.

Fix an issue with the RStudio IDE when using knitr::include_url() or knitr::include_app() in interactive Notebook mode. This will no more cause an error but print the list object as is (thanks, @systemnova, #2015).
Fix a regression with fig.keep chunk option used in chunks with only one figure where the figure was not showing in output (thanks, @fmichonneau, #1993).
Allow vignettes to be tangled (and output compared) in R CMD check if they have a corresponding .Rout.save (thanks, @lentinj, #2018).