[Rd] data() misbehaving inside a function

Martin Maechler maechler at stat.math.ethz.ch
Fri Oct 17 09:28:59 MEST 2003

>>>>> "KH" == Kurt Hornik <Kurt.Hornik at wu-wien.ac.at>
>>>>>     on Fri, 17 Oct 2003 09:04:40 +0200 writes:

>>>>> Peter Dalgaard writes:
    >> David James <dj at research.bell-labs.com> writes:
    >>> Calls of the form data(package = pkg) inside a function 
    >>> incorrectly fail ("pkg" is a local variable).  For instance,
    >>> foo <- function(pkg) data(package = pkg)
    >>> foo("base")
    >>> Error in .find.package(package, lib.loc, verbose = verbose) :
    >>> none of the packages were found

    >> This is pretty much unavoidable if you want a function to accept
    >> unquoted names. It's not in principle different from

    >> women <- "airquality"
    >> data(women)

    >> not being equivalent to data("airquality"). Some functions (library(),
    >> require(), demo()) have a character.only argument to prevent it, and I
    >> suppose we should consider putting it on help() and data() as well.

    KH> Or get rid of non-standard evaluation and educate users to use quoted
    KH> strings where strings should be used.

and infuriate those who know and used the S language for more
than 15 years, where  help(help)  has always worked? 

Definitely not worth the pain (I *know* I'd hear ... comments from them!)!
I'd go for adding `character.only'.


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