Reissue: Base "Object" class to use in S4 slot specification

On Sep 8, 2009, at 12:14 , Patrick Aboyoun wrote:

This is a reissue of a question I had asked a few weeks ago to see  
if anyone had any thoughts on the matter.

I am looking to have slot in an S4 class definition that can take  
any (S3 or S4) object. The ANY class seemed to be a good candidate,  
but the is() function definition performs an S3Case test before  
checking if methods:::.identC(class2, "ANY"). The result is the  
is() function does not consider various S3 objects to be of class  
ANY.

Yes, but how is that relevant to your question? A slot defined as  
"ANY" will accept any type in R:

setClass("foo",representation(a="ANY"))

[1] "foo"

new("foo",a=factor())

An object of class "foo"
Slot "a":
factor(0)
Levels:

"ANY" is not an S4 class (and neither are various other types in R),  
so is() correctly returns FALSE.

is(factor(), "ANY")

[1] FALSE

is(lm(I(1:10) ~ rnorm(10)), "ANY")

[1] FALSE

sessionInfo()

R version 2.10.0 Under development (unstable) (2009-09-07 r49613)
i386-apple-darwin9.8.0

locale:
[1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base
What is the recommended base "Object" class I should define my slot  
to be so it can accept any object?



Patrick