VIGNETTES: Add example on 'arrow' for non-exportable objects

DESCRIPTION

@@ -1,5 +1,5 @@
 Package: future
-Version: 1.33.1-9004
+Version: 1.33.1-9005
 Title: Unified Parallel and Distributed Processing in R for Everyone
 Imports:
     digest,

vignettes/future-4-non-exportable-objects.md.rsp

@@ -75,6 +75,7 @@ _If you identify other cases, please consider [reporting](https://github.com/Hen
 
   Package         | Examples of non-exportable types or classes
   :---------------|:-------------------------------------------
+  **arrow**       | Table (`externalptr`)
   **base**        | connection (`externalptr`)
   **cpp11**       | E.g. functions created by `cpp_source()`
   **DBI**         | DBIConnection (`externalptr`)
@@ -144,6 +145,37 @@ However, there are objects with _external pointer_:s that can be exported, e.g.
 Below are some examples of packages who produce non-exportable objects with _external pointer_:s.
 
 
+#### Package: arrow
+
+The **[arrow]** package provides efficient in-memory storage of arrays
+and tables.  How, these objects cannot be transferred as-is to a
+parallel workers.
+
+```r
+library(arrow)
+
+library(future)
+plan(multisession)
+
+data <- as_arrow_table(iris)
+
+f <- future(dim(data))
+v <- value(f)
+#> Error: Invalid <Table>, external pointer to null
+```
+
+This error takes place on the parallel worker.  We can use:
+
+```r
+options(future.globals.onReference = "error")
+f <- future(dim(data))
+#> Error: Detected a non-exportable reference ('externalptr') in one of the globals
+#> ('data' of class 'Table') used in the future expression
+```
+
+to help us detect the problem sooner.
+
+
 #### Package: cpp11
 
 Another example is **[cpp11]**, which allows us to easily create R functions that are implemented in C++, e.g.
@@ -987,6 +1019,7 @@ str(e)
 
 
 [data.table]: https://cran.r-project.org/package=data.table
+[arrow]: https://cran.r-project.org/package=arrow
 [cpp11]: https://cran.r-project.org/package=cpp11
 [DBI]: https://cran.r-project.org/package=DBI
 [inline]: https://cran.r-project.org/package=inline