Full_Name: Thomas Friedrichsmeier
Version: 2.4.0
OS: GNU/Linux
Submission from: (NULL) (84.61.116.51)
Since R 2.4.0, operator "::" also returns objects in the package environment, if
the package does not have a namespace. This is a very welcome addition.
Additional wish:
If a package has a namespace, but does not place all symbols in that namespace,
lookup will still fail. For example in package boot (version 1.2-26):
library (boot)
exists ("motor", envir=as.environment ("package:boot")) # TRUE
getAnywhere ("motor") # found in
package:boot
boot::motor # error not in
namespace
This is as documented, but I think it would be convenient, if boot::motor would
also return the object in this case.
This might be achieved by adding an additional tryCatch in "::": If the package
has a namespace, try getExportedValue (), if that fails, try to get from package
environment instead. E.g.:
"::" <- function (pkg, name)
{
pkg <- as.character(substitute(pkg))
name <- as.character(substitute(name))
ns <- tryCatch(asNamespace(pkg), hasNoNamespaceError = function(e) NULL)
if (is.null(ns)) {
pos <- match(paste("package", pkg, sep = ":"), search(),
0)
if (pos == 0)
stop(gettextf(paste("package '%s' has no name space and",
"is not on the search path"), pkg), domain = NA)
get(name, pos = pos, inherits = FALSE)
}
else tryCatch(getExportedValue(pkg, name), error=function (e) {
pos <- match(paste("package", pkg, sep=":"), search(),
0)
get(name, pos, inherits=FALSE)
})
}
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