Can the class definition in package "foo" be changed after the package is
attached?  I am trying to do the following.

The AllClasses.R file has the following class definitions.

setClassUnion("mymatrix", c("mymatrix"))
setClass("mydata", representation(x="numeric", y="cnmatrix"))

In zzz.R the .onLoad has the following:

  setHook(packageEvent("bigmemory", "attach"),
          function(...){
            setIs("big.matrix", "cnmatrix")
            setClass("mydata", representation(x="numeric", y="cnmatrix")
          })

When I now do R CMD check pkg it is completed but I get a note

* checking R code for possible problems ... NOTE
Error in setIs("big.matrix", "cnmatrix") :
  cannot create a 'setIs' relation when neither of the classes ("big.matrix"
and "cnmatrix") is local and modifiable in this package

How do I modify the definition of a class in a package?

Thanks,
Venkat

My R.Version()
$platform
[1] "x86_64-pc-linux-gnu"

$arch
[1] "x86_64"

$os
[1] "linux-gnu"

$system
[1] "x86_64, linux-gnu"

$status
[1] ""

$major
[1] "2"

$minor
[1] "11.1"

$year
[1] "2010"

$month
[1] "05"

$day
[1] "31"

$`svn rev`
[1] "52157"

$language
[1] "R"

$version.string
[1] "R version 2.11.1 (2010-05-31)"

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