use a different method to fix #1798 because R CMD check doesn't like the unlockBinding() call

Author: yihui

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: knitr
 Type: Package
 Title: A General-Purpose Package for Dynamic Report Generation in R
-Version: 1.43.16
+Version: 1.43.17
 Authors@R: c(
     person("Yihui", "Xie", role = c("aut", "cre"), email = "xie@yihui.name", comment = c(ORCID = "0000-0003-0645-5666")),
     person("Abhraneel", "Sarma", role = "ctb"),

R/block.R

@@ -52,7 +52,7 @@ call_block = function(block) {
   }
 
   # save current chunk options in opts_current
-  opts_current$unlock(); opts_current$restore(params)
+  opts_current$restore(params)
 
   if (opts_knit$get('progress')) print(block)
 
@@ -112,7 +112,7 @@ call_block = function(block) {
   opts_current$restore(params)  # save current options
   # prevent users from modifying opts_current (#1798)
   if (!xfun::check_old_package('lingglosses', '0.0.6'))  # TODO: remove this hack https://github.com/agricolamz/lingglosses/issues/22
-  opts_current$lock(); on.exit(opts_current$unlock(), add = TRUE)
+  opts_current$lock(); on.exit(opts_current$lock(FALSE), add = TRUE)
 
   # set local options() for the current R chunk
   if (is.list(params$R.options)) {

R/defaults.R

@@ -2,6 +2,7 @@
 
 new_defaults = function(value = list()) {
   defaults = value
+  locked = FALSE
 
   get = function(name, default = FALSE, drop = TRUE) {
     if (default) defaults = value  # this is only a local version
@@ -20,7 +21,10 @@ new_defaults = function(value = list()) {
   }
   set2 = function(values) {
     old = get(names(values), drop = FALSE)
-    if (length(values)) defaults <<- merge(values)
+    if (length(values)) {
+      if (locked) stop('The object is read-only and cannot be modified.')
+      defaults <<- merge(values)
+    }
     invisible(old)
   }
   set = function(...) {
@@ -36,13 +40,11 @@ new_defaults = function(value = list()) {
     for (i in names(dots)) dots[[i]] <- c(defaults[[i]], dots[[i]])
     set2(dots)
   }
-  env = environment()
-  lock = function() lockBinding('defaults', env)
-  unlock = function() unlockBinding('defaults', env)
+  lock = function(status = TRUE) locked <<- status
 
   list(
     get = get, set = set, delete = delete, append = append, merge = merge,
-    restore = restore, lock = lock, unlock = unlock
+    restore = restore, lock = lock
   )
 }
 

R/output.R

@@ -156,7 +156,7 @@ knit = function(
     on.exit({
       opts_chunk$restore(optc)
       knit_code$restore(ocode)
-      opts_current$unlock(); opts_current$restore()
+      opts_current$restore()
       opts_knit$restore(optk)
     }, add = TRUE)
     opts_knit$set(