-----Original Message-----
From: Martin Morgan [mailto:mtmorgan at fhcrc.org]
Sent: 13 January 2009 16:31
To: Sklyar, Oleg (London)
Cc: r-devel at r-project.org
Subject: Re: [Rd] particulars of importing/loading libraries
Hi Oleg --
"Sklyar, Oleg (London)" <osklyar at maninvestments.com> writes:
Dear List:
Sorry for posting maybe a trivial question, but I have a basic
understanding problem. If I have say pack1 and pack2, two R
and pack2 depends on and imports pack1 fully (as in the
there a way to make all the functionality of pack1 available for the
global and other environments (not only for the functions
withing pack2) by loading pack2 only? I thought if pack2
imports pack1 and essentially reexports everything, one
full functionality simply by loading pack2. This does not
case or I am missing something trivial in my NAMESPACE/DESCRIPTION
files?
I think that exportPattern does a simple ls() on the environment of
the package name space. The imported symbols are not defined in that
environment, but (I think) in a variable .__NAMESPACE__. and so are
not discovered. Arguably, exportPattern (and friends) should be
smarter. Pragmatically, you need to re-export imported symbols
explicitly. I haven't worked this through entirely, and could be
wrong...
Martin
If this is documented in Writing R Extensions, I would be
page number and maybe a quick fix in my example below as so
not been able to find a clear explanation.
The problem can be illustrated by the following simple
a simple code for 2 packages, pack1 and pack2; plus an example).
Thank you for your replies.
Dr Oleg Sklyar
Research Technologist
AHL / Man Investments Ltd
+44 (0)20 7144 3107
osklyar at maninvestments.com
--- pack1: DESCRIPTION ------
Package: pack1
Version: 0.0.1
Date: 12 Jan 2009
Title: pack1 to test S3/S4 methods compatibility
Author: Oleg Sklyar
Depends: R (>= 2.7.1), methods
Maintainer: Oleg Sklyar <osklyar at maninvestments.com>
Description: pack1
LazyLoad: yes
License: Proprietary
URL: http://www.maninvestments.com
LazyLoad: no
--- pack1: NAMESPACE ------
import(methods)
exportPattern("^[^\\.]")
exportClasses(posixTime)
exportMethods(as.POSIXct)
--- pack1: posix.R ------
setClass("posixTime", "numeric")
setGeneric("as.POSIXct")
setMethod("as.POSIXct", signature(x="posixTime"),
function(x, tz) {
z = x at .Data
attr(z,"class") = c("POSIXt", "POSIXct")
attr(z,"tzone") = "UTC"
z
}
)
testPosixVal = new("posixTime", as.numeric(Sys.time()))
--- pack2: DESCRIPTION
Package: pack2
Version: 0.0.1
Date: 12 Jan 2009
Title: pack2 to test S3/S4 methods compatibility
Author: Oleg Sklyar
Depends: R (>= 2.7.1), methods
Maintainer: Oleg Sklyar <osklyar at maninvestments.com>
Description: pack2
LazyLoad: yes
License: Proprietary
URL: http://www.maninvestments.com
LazyLoad: no
--- pack2: NAMESPACE ------
import(pack1)
exportPattern("^[^\\.]")
--- pack2: posix.R ------
testPosix = function() {
z = as.POSIXct(testPosixVal)
print(z)
print(class(z))
z
}
------ test code to run from global env, showing problems -------
require(pack2)
## use as.POSIXct imported into pack2 from pack1 to do the
the fun
testPosix()
#~ [1] "2009-01-13 15:29:50 UTC"
#~ [1] "POSIXt" "POSIXct"
#~ [1] "2009-01-13 15:29:50 UTC"
## now try using it directly from the global env (pack1 was not
explicitly loaded)
as.POSIXct(pack1::testPosixVal)
#~ Error in as.POSIXct.default(pack1::testPosixVal) :
#~ do not know how to convert 'pack1::testPosixVal' to
## now require pack1 explicitly and try again
require(pack1)
as.POSIXct(pack1::testPosixVal)
#~ [1] "2009-01-13 15:29:50 UTC"
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