[Rd] check does not check that package examples remove tempdir()

[William Dunlap]

I was looking at the CRAN package 'bfork-0.1.2', which exposes the Unix
fork() and waitpid() calls at the R code level, and noticed that the help
file example for bfork::fork removes R's temporary directory, the value of
tempdir().   I think it happens because the forked process shares the value
of tempdir() with the parent process and removes it when it exits.

This seems like a serious problem - should 'check' make sure that running
code in a package's examples, vignettes, etc. leaves tempdir() intact?

> dir.exists(tempdir())
[1] TRUE
> library(bfork)
> example(fork)

fork>     ## create a function to be run as a separate process
fork>     fn <- function() {
fork+         Sys.sleep(4)
fork+         print("World!")
fork+     }

fork>     ## fork the process
fork>     pid <- fork(fn)

fork>     ## do work in the parent process
fork>     print("Hello")
[1] "Hello"

fork>     ## wait for the child process
fork>     waitpid(pid)
[1] "World!"
[1] 7063
> dir.exists(tempdir())
[1] FALSE


Bill Dunlap
TIBCO Software
wdunlap tibco.com

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