restore opts_current after each code chunk, and also after knit()…

… exits (#2292)

also add labels to `opts_current` for inline code to fix #1988

NEWS.md

@@ -4,6 +4,10 @@
 
 - Improved the error message to contain more specific information when YAML chunk options could not be parsed (thanks, @pedropark99, #2294).
 
+## MAJOR CHANGES
+
+- The object `opts_current` will be restored after each code chunk has finished executing. Previously, it would not be restored, which means even for inline R expressions, `opts_current$get()` will inherit chunk options from a previous code chunk (thanks, @rundel, #1988). Besides, `opts_current$get('label')` will return a unique label for inline expressions. One possible application is to construct unique figure paths via `fig_path()` (e.g., ropensci/magick#310).
+
 ## BUG FIXES
 
 - Special characters in the chunk option `fig.alt` are properly escaped now (thanks, @jay-sf, #2290).

R/block.R

@@ -52,6 +52,7 @@ call_block = function(block) {
   }
 
   # save current chunk options in opts_current
+  optc = opts_current$get(); on.exit(opts_current$restore(optc), add = TRUE)
   opts_current$restore(params)
 
   if (opts_knit$get('progress')) print(block)
@@ -545,6 +546,9 @@ merge_character = function(res) {
 }
 
 call_inline = function(block) {
+  optc = opts_current$get(); on.exit(opts_current$restore(optc), add = TRUE)
+  params = opts_chunk$merge(list(label = unnamed_chunk()))
+  opts_current$restore(params)
   if (opts_knit$get('progress')) print(block)
   in_input_dir(inline_exec(block))
 }

R/output.R

@@ -151,14 +151,10 @@ knit = function(
       useFancyQuotes = FALSE, device = pdf_null, knitr.in.progress = TRUE
     )
     on.exit(options(oopts), add = TRUE)
-    # restore chunk options after parent exits
-    optc = opts_chunk$get(); ocode = knit_code$get(); optk = opts_knit$get()
-    on.exit({
-      opts_chunk$restore(optc)
-      knit_code$restore(ocode)
-      opts_current$restore()
-      opts_knit$restore(optk)
-    }, add = TRUE)
+    # restore objects like chunk options after parent exits
+    opta = list(opts_chunk, opts_current, knit_code, opts_knit)
+    optv = lapply(opta, function(o) o$get())
+    on.exit(for (i in seq_along(opta)) opta[[i]]$restore(optv[[i]]), add = TRUE)
     opts_knit$set(
       output.dir = getwd(),  # record working directory in 1st run
       tangle = tangle, progress = opts_knit$get('progress') && !quiet