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

[Dan Tenenbaum]

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
> 
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