On 2018-04-26 07:11, Jose A Guijarro wrote:
El 25/04/18 a las 20:21, Duncan Murdoch escribió:
On 25/04/2018 1:32 PM, Sarah Goslee wrote:
Don't change the working directory! That has all kinds of unpleasant
side effects for the unsuspecting user, possibly even more so than
writing to a file.
Instead, write the file to the temp directory, and read it from
there, with e.g.
wd <- tempdir()
write(dat, file.path(wd, 'Ttest_1981-2000.dat'))
Using file.path() means that the appropriate path delimiter for that
OS will be used.
That's one good way to do it. But it is possible to change directory
and change back at the end of the example. For example,
wd <- tempdir()
savedir <- setwd(wd)
... # the original code that writes and reads in the current dir
setwd(savedir)
There's a worry that an error in the middle of the code will leave
the user in the wrong place. If that's really unlikely to happen,
then this code is a little simpler than Sarah's suggestion.
If it is likely, you can use tryCatch(..., finally = setwd(savedir)),
but I think Sarah's solution would be preferable in most cases: many
users will not understand what tryCatch() does.
Hi, Duncan, et al.:
Under what circumstances should one also use "on.exit":
wd <- tempdir()
savedir <- setwd(wd)
on.exit(setwd(savedir))?
Even senior R programmers may miss a failure mode. In a
function, this works well: I don't need to remember to "setwd(savedir)"
later in the code, which could be a problem if I have multiple exit
points. I don't know how it would work in a vignette or the examples
section of a *.Rd file. tryCatch(..., finally = setwd(savedir))
condenses this into one line ... and is too terse for me in many cases.
Spencer Graves
Duncan Murdoch
Many thanks for the suggestion! In this way I only need to apply
slight changes in the examples and can avoid modifying all read/writes
along the package. I will try this approach and see if it passes the
CRAN checks.
Jose
Sarah
On Wed, Apr 25, 2018 at 12:30 PM, Jose A Guijarro
<jguijar...@aemet.es> wrote:
Dear all,
I am struggling to update my package climatol from version 3.0 to 3.1.
The old version had all examples under a "dontrun" section because
they
needed files created by other examples that the user had to run first.
As this is not acceptable anymore, I made the examples runnable and
prepared small ad-hoc datasets, but then writing files to the user
space
is against the CRAN policy rules, and I was suggested to run them on a
temporal directory. Therefore I changed all my examples to read/write
files to a tempdir(), as in:
\examples{
#Set a temporal working directory and write input files:
wd <- tempdir()
setwd(wd)
data(Ttest) #(This loads matrix 'dat' and data.frame 'est.c')
write(dat,'Ttest_1981-2000.dat')
write.table(est.c,'Ttest_1981-2000.est',row.names=FALSE,col.names=FALSE)
rm(dat,est.c) #remove loaded data from memory space
#Now run the example:
dd2m('Ttest',1981,2000)
#Input and output files can be found in directory:
print(wd)
}
But now CRAN checks return this warning ten times (one for every
example
in the package):
Warning: working directory was changed to ‘/tmp/RtmpWSRK2F’, resetting
Any hint on how to solve the problem will be highly appreciated...
Jose
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