[R-pkg-devel] Options "reset" when options(opts)

[David Hugh-Jones]

This surprised me, even though it shouldn’t have done. (My false internal
model of the world was that oo <- options(); … options(oo) would overwrite
the entire options list with the old values.) I wonder if it would be worth
pointing out explicitly in ?options.

Writing: wyclif.substack.com
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On Thu, 11 Jul 2024 at 08:03, Greg Jefferis <jefferis using gmail.com> wrote:

> Dear John,
>
> You need to collect the return value when setting options. This will
> include an explicit NULL value for an option that was previously NULL.
>
> Best,
>
> Greg Jefferis.
>
> options(digits.secs = NULL)
>
> noset2 = function() {
>   opts <- options(digits.secs = 3)
>   on.exit(options(opts))
>   print(opts)
> }
>
> > getOption("digits.secs")
> NULL
>
> > noset2()
> $digits.secs
> NULL
>
> > getOption("digits.secs")
> NULL
>
> Gregory Jefferis
> Division of Neurobiology
> MRC Laboratory of Molecular Biology
> Francis Crick Avenue
> Cambridge Biomedical Campus
> Cambridge, CB2 OQH, UK
>
> http://www2.mrc-lmb.cam.ac.uk/group-leaders/h-to-m/g-jefferis
> http://jefferislab.org
> https://www.zoo.cam.ac.uk/research/groups/connectomics
>
>
> > On 11 Jul 2024, at 06:08, John Muschelli <muschellij2 using gmail.com> wrote:
> >
> > When setting options in a function, I have always used the following:
> >  opts <- options()
> >  on.exit(options(opts), add = TRUE)
> > and assumed it "reset" options to what they were prior to running the
> > function.  But for some options that are set to NULL, it does not seem to
> > reset them.  Specifically, I have found digits.secs to be set after this
> > simple example below.  Is this expected behavior/documented?  Overall,
> this
> > specific example (the one I encountered in the wild) is not that harmful,
> > but I wanted to ask before I set a fix for this in our work
> >
> > noset = function() {
> >  opts = options()
> >  print(opts$digits.secs)
> >  on.exit(options(opts))
> >  options(digits.secs = 3)
> > }
> > getOption("digits.secs")
> > #> NULL
> > noset()
> > #> NULL
> > getOption("digits.secs")
> > #> [1] 3
> >
> >
> > John Muschelli, PhD
> > Associate Research Professor
> > Department of Biostatistics
> > Johns Hopkins Bloomberg School of Public Health
> >
> > [[alternative HTML version deleted]]
> >
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>
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