close #2368: wrap code chunk in try() for purl() when the chunk optio…

…n `error = TRUE` (#2380)

also close #2338

NEWS.md

@@ -18,6 +18,8 @@
 
 - Unbalanced chunk delimiters (fences) in R Markdown documents are strictly prohibited now.
 
+- For code chunks with `error = TRUE`, `purl()` and `hook_purl()` will wrap the code in `try({...})` (thanks, @bastistician #2338, @jeroen #2368).
+
 ## MINOR CHANGES
 
 - Changed the format of the reference card from PDF to HTML so building this package will not require LaTeX. See `vignette('knitr-refcard', package = 'knitr')`.

R/block.R

@@ -605,12 +605,18 @@ tangle_block = function(x) {
     eval(parse_only(unlist(str_extract(code, 'read_chunk\\(([^)]+)\\)'))))
   }
   code = parse_chunk(code)
-  if (isFALSE(ev)) code = comment_out(code, params$comment, newline = FALSE)
+  code = tangle_mask(code, ev, x$params$error)
   if (opts_knit$get('documentation') == 0L) return(one_string(code))
   # e.g. when documentation 1 or 2 with purl()
   label_code(code, x)
 }
 
+tangle_mask = function(code, eval, error) {
+  if (isFALSE(eval)) code = comment_out(code, '#', newline = FALSE)
+  if (isTRUE(error)) code = c('try({', code, '})')
+  code
+}
+
 tangle_inline = function(x) {
   output = if (opts_knit$get('documentation') == 2L) {
     output = paste("#'", gsub('\n', "\n#' ", x$input, fixed = TRUE))

R/hooks-extra.R

@@ -146,8 +146,10 @@ hook_purl = function(before, options, ...) {
     .knitEnv$tangle.params = NULL
   }
 
-  code = options$code
-  if (isFALSE(options$eval)) code = comment_out(code, '# ', newline = FALSE)
+  # `options` contains merged chunk options, but we need to check if
+  # `error=TRUE` in local chunk options, so retrieve options from knit_code
+  error = attr(knit_code$get(options$label), 'chunk_opts')[['error']]
+  code = tangle_mask(options$code, options$eval, error)
   if (is.character(output)) {
     code = c(
       if (file.exists(output)) read_utf8(output),