[Bioc-devel] testing class and length of function args

On Wed, 22 Jul 2015, Michael Love wrote:

 it's slightly annoying to write

foo <- function(x) {
 if ( ! is.numeric(x) ) stop("x should be numeric")
 if ( ! length(x) == 2 ) stop("x should be length 2")
 c(x[2], x[1])
}

i wonder if we could have some core functions that test the class and
the length in one and give the appropriate stop message.

maybe this exists already

Not what you are asking, but perhaps this saves you a step:

        stopifnot( is.numeric(x), length(x)==2 )

stopifnot( ... ) will stop and issue an error msg for the first arg that
is FALSE.

HTH,

Chuck