[R] using S4 objects in "with"?

[Spencer Graves]

       Is there anything comparable to "with" for S4 objects?


EXAMPLE:


       A "Wave" object in the tuneR package has slots "left" and 
"right", plus others.  I'd like to be able to do something like the 
following:


library(tuneR)
x <- seq(0, 2*pi, length = 6)
all.equal(x, rev(x))
channel <- round(32000 * sin(440 * x))
Wobj <- Wave(left = channel, right=rev(channel))

with(Wobj, quantile(left-right))


       ** This last statement throws "Error ... object 'left' not found".


       Is there something comparable to "with" that can do this?


       Thanks,
       Spencer Graves