[Rd] class() on substitute(...) output?
Henrik Bengtsson
hb at biostat.ucsf.edu
Fri Jan 3 02:16:25 CET 2014
Does it make sense to talk about the class of the output of
substitute(...)? I'm puzzled by the following outputs:
ee <- list(
A = substitute( a <- 1 ),
B = substitute({ a <- 1 }),
C = substitute(( a <- 1 )),
D = substitute( a == 1 )
)
> t(sapply(ee, FUN=function(e) { c(typeof=typeof(e), mode=mode(e), class=class(e)) }))
typeof mode class
A "language" "call" "<-"
B "language" "call" "{"
C "language" "(" "("
D "language" "call" "call"
That the mode in C is "(", is motivated in help("mode"): "that some
calls have mode "(" which is S compatible." However, what's the
explanation for the different classes? Is that intended or just
"garbage" output?
Thanks,
Henrik
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