[R-pkg-devel] Writing to files without altering working directory in R package

[Duncan Murdoch]

On 07/05/2019 6:44 p.m., Uwe Ligges wrote:
> 
> 
> On 07.05.2019 19:57, Duncan Murdoch wrote:
>> 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.
> 
> Thank you, Duncan. Well, setwd(tempdir()) should be made local to the
> examples if used at all, as the user may not expect to have the working
> directory changed.

Yes, I agree.

Duncan Murdoch