[GitHub] [arrow] ianmcook commented on a change in pull request #9168: ARROW-10834: [R] Fix print method for SubTreeFileSystem

[GitBox <gi...@apache.org>]

ianmcook commented on a change in pull request #9168:
URL: https://github.com/apache/arrow/pull/9168#discussion_r555361025



##########
File path: r/R/filesystem.R
##########
@@ -418,10 +418,12 @@ SubTreeFileSystem$create <- function(base_path, base_fs = NULL) {
 `$.SubTreeFileSystem` <- function(x, name, ...) {
   # This is to allow delegating methods/properties to the base_fs
   assert_that(is.string(name))
-  if (name %in% ls(x)) {
+  if (name %in% ls(envir = x)) {
     get(name, x)
-  } else {
+  } else if (name %in% ls(envir = x$base_fs)) {
     get(name, x$base_fs)
+  } else {
+    NULL

Review comment:
       Using `envir` in these `ls()` calls stops this cryptic warning from being issued when the external pointer breaks:
   ```
   In addition: Warning message:
   In ls(x$base_fs) : ‘x$base_fs’ converted to character string
   ```
   That warning comes from a part of the code in `ls()` that doesn't run if you pass the object as `envir`.




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