On 05/10/2015 08:19 AM, Martin Morgan wrote:
Loading an S4 object from a file without first loading the library sometimes (?,
the example below and actual example involves a virtual base class and the show
generic) leads to incorrect dispatch (to the base class method).
The attached package reproduces the problem. It has
The package was attached but stripped; a version is at
https://github.com/mtmorgan/PkgA
FWIW the sent mail was a multi-part MIME with the header on the package part
Content-Type: application/gzip;
name="PkgA.tar.gz"
Content-Transfer-Encoding: base64
Content-Disposition: attachment;
filename="PkgA.tar.gz"
From http://www.r-project.org/mail.html#instructions "we allow application/pdf,
application/postscript, and image/png (and x-tar and gzip on R-devel)" so I
thought that this mime type would not be stripped?
Martin Morgan
setClass("A")
setClass("B", contains="A")
setMethod("show", "A", function(object) cat("A\n"))
setMethod("show", "B", function(object) cat("B\n"))
with NAMESPACE
import(methods)
exportClasses(A, B)
exportMethods(show)
This creates the object and illustrated expected behavior
~/tmp$ R --vanilla --slave -e "library(PkgA); b = new('B'); save(b,
file='b.Rda'); b"
B
Loading PkgA before the object leads to correct dispatch
~/tmp$ R --vanilla --slave -e "library(PkgA); load(file='b.Rda'); b"
B
but loading the object without first loading PkgA leads to dispatch to
show,A-method.
~/tmp$ R --vanilla --slave -e "load(file='b.Rda'); b"
Loading required package: PkgA
A
Martin Morgan
--
Computational Biology / Fred Hutchinson Cancer Research Center
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Phone: (206) 667-2793
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