[Rd] require(..., quietly=TRUE) does not suppress warning

[Kevin Ushey]

IMHO the strongest argument for suppressing the warning message here is the
fact that

    requireNamespace("foo", quietly = TRUE)

does not emit any warning message when the package 'foo' does not exist.

On Thu, Dec 8, 2016 at 12:51 PM, Dan Tenenbaum <dtenenba at fredhutch.org>
wrote:

> Well, I'm getting a warning (not an error) when the package doesn't exist.
> I interpreted "most often" to mean that suppressing warnings/errors is why
> you'd most often use this argument, as most packages don't emit startup
> messages.
>
> And technically there isn't a problem with attaching the package, since we
> don't even try to attach packages that don't exist.
>
> So yes, very careful parsing of the docs suggests that the behavior is
> correct, but it does seem to violate the 'spirit' of what a user might
> expect. I am pretty sure I have used the 'if (!require("pkg"))
> install.packages("pkg")' pattern before without seeing this warning, so I
> wondered if the behavior had changed, and that's what prompted me to write.
>
> I know I can squelch the warning by wrapping the require() in
> suppressWarnings().
>
> Dan
>
>
> ----- Original Message -----
> > From: "John P. Nolan" <jpnolan at american.edu>
> > To: "Dan Tenenbaum" <dtenenba at fredhutch.org>, "R-devel" <
> r-devel at r-project.org>
> > Sent: Thursday, December 8, 2016 12:37:02 PM
> > Subject: RE: require(..., quietly=TRUE) does not suppress warning
>
> > Well, it says "most often" no errors/warnings are given, so it is not
> > contradicting the docs!   It looks like the person/team that coded
> require( )
> > decided you should get an error when the package doesn't exist.
> >
> > If you want a silent loading, consider
> >     aaa <- try( library(foo,verbose=FALSE,quietly=TRUE),silent=TRUE)
> > and then check to see if aaa is of class "try-error" and check for
> failure
> >
> > John
> > ………………………………………………………………………………..
> >
> > John P. Nolan
> > Math/Stat Dept., American University
> > Gray Hall, 4400 Massachusetts Ave, NW
> > Washington, DC 20016-8050
> > Phone: 202-885-3140
> > E-mail:  jpnolan at american.edu
> > Web:   http://fs2.american.edu/jpnolan/www/
> >
> >
> >
> > -----Original Message----
> > From: R-devel [mailto:r-devel-bounces at r-project.org] On Behalf Of Dan
> Tenenbaum
> > Sent: Thursday, December 8, 2016 2:43 PM
> > To: R-devel <r-devel at r-project.org>
> > Subject: [Rd] require(..., quietly=TRUE) does not suppress warning
> >
> > Hi,
> >
> > The `quietly` argument of `require` is documented as follows:
> >
> > quietly: a logical.  If ‘TRUE’, no message confirming package
> >          attaching is printed, and most often, no errors/warnings are
> >          printed if package attaching fails.
> >
> > However:
> >
> >> require(foo, quietly=TRUE)
> > Warning message:
> > In library(package, lib.loc = lib.loc, character.only = TRUE,
> logical.return =
> > TRUE,  :
> >  there is no package called ‘foo’
> >
> > Am I misreading the docs or is R misbehaving?
> >
> >> sessionInfo()
> > R version 3.3.2 (2016-10-31)
> > Platform: x86_64-apple-darwin13.4.0 (64-bit) Running under: macOS Sierra
> 10.12.1
> >
> > locale:
> > [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
> >
> > attached base packages:
> > [1] stats     graphics  grDevices utils     datasets  methods   base
> >
> > Dan
> >
> > ______________________________________________
> > R-devel at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
>
> ______________________________________________
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