On 06/05/2019 12:16 p.m., Jim Hester wrote:
For what it's worth, the recommendation to use `tempfile()` is very
confusing to R users.
Often users (particularly new users) jump directly to examples when
reading documentation and when you have these more complicated
examples they do not realize they can just use a simple string
literal.
See https://github.com/tidyverse/readr/issues/635 for an issue where
multiple users explicitly request examples which do _not_ use
`tempfile()`.
I think beginners rarely like the help pages, and that's really to be
expected: help pages need to be complete and correct, and beginners
really need a small subset of possibilities. Beginners need tutorials.
In the Github issue, you mentioned pollution of the working directory,
but I think a bigger problem is destruction of user data, e.g. if a user
has a file "wine.csv", and the example writes to that file.
So you need to do something to protect users. I think making examples a
little complicated by using setwd(tempdir()) with a literal filename, or
writing to tempfile() is worth it.
Duncan Murdoch
On Fri, May 3, 2019 at 7:59 PM Duncan Murdoch <murdoch.dun...@gmail.com> wrote:
On 03/05/2019 6:33 p.m., Jarrett Phillips wrote:
Hello,
My R package has a function with an argument to specify whether numerical
results should be outputted to a CSV file.
CRAN policy stipulates verbatim that
Packages should not write in the user’s home filespace (including
clipboards), nor anywhere else on the file system apart from the R
session’s temporary directory (or during installation in the location
pointed to by TMPDIR: and such usage should be cleaned up). Installing into
the system’s R installation (e.g., scripts to its bin directory) is not
allowed.
I know I should use tempdir() within my package function, but I've not seen
any examples on how this is best done within existing R packages.
Within my package documentation examples for my function, I have the lines:
\dontshow{.oldwd <- setwd(tempdir())}
... some R code ...
\dontshow{setwd(.oldwd)}
but I have been informed that this is not the accepted way.
Any ideas from the community on how do do this properly?
Use the tempfile() function to generate a filename in the temporary
directory. You might want to use the "pattern" or "fileext" arguments,
but don't change the "tmpdir" argument.
Then write to that file.
For example,
filename <- tempfile(fileext = ".csv")
write.csv(df, filename)
It's a good idea to clean up afterwards using
unlink(filename)
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