fUtilities::isS4

[Phil Spector]

Hi!
    I'm having some difficulties using the isS4 function in 
the fUtilities package.  Specifically, I think that the 
test for NULL slotNames may not always give the correct 
result.

For example, consider an lm object:

> x = rnorm(10)
> y = rnorm(10)
> z = lm(y~x)
> base::isS4(z)
[1] FALSE
> fUtilities::isS4(z)
[1] TRUE
> slotNames(z)
[1] ".S3Class"

     Since showMethods(class='lm') doesn't return anything, I don't
think lm objects should be identified as S4 objects by isS4.

     Thanks!
                                        - Phil Spector
 					 Statistical Computing Facility
 					 Department of Statistics
 					 UC Berkeley
 					 spector at stat.berkeley.edu