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

[Simon Urbanek]

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.

Cheers,
Simon


> > 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
>
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