Yes, but this is not to do with being inside a function:
pkg <- "base"
data(package=pkg)
ilustrates it, and library etc behave in the same way (except
library can make use of character.only = TRUE).
You can use substitute, too, as in
foo <- function(pkg) eval(substitute(data(package = pkg), list(pkg=pkg)))
On Thu, 16 Oct 2003, David James wrote:
> 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
>
> ## workaround -- force argument "package" to be an expression
> ## (not a name)
>
> foo <- function(pkg) data(package = as.character(pkg))
> all.equal(data(package = "base"), foo("base"))
> [1] TRUE
>
> The cause is the following piece of code inside data()
>
> > print(data)
> ....
> if (!missing(package))
> if (is.name(y <- substitute(package)))
> package <- as.character(y)
> ...
>
> namely, when data() is invoked from within a function, e.g.,
> data(package = pkg), the argument "package" inside data() is indeed
> a name, but not one that should be coerced to character as when one
> types data(base) from the R prompt, but rather simply a variable
> in the calling function; in the example above, the arg "package"
> to data() is effectively computed to be "pkg", which (luckily)
> does not correspond to any attached package.
>
> version
> _
> platform i686-pc-linux-gnu
> arch i686
> os linux-gnu
> system i686, linux-gnu
> status Patched
> major 1
> minor 8.0
> year 2003
> month 10
> day 13
> language R
>
>
--
Brian D. Ripley, [EMAIL PROTECTED]
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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