On 10/25/2006 8:14 PM, Gabor Grothendieck wrote: > Suppose we have a function such as the following > > F <- function(f, x) f(x)+1 > > which runs function f and then transforms it. I would like the > corresponding function which works the same except that > unlike F returns an invisible result if and only if f does. > > Is there some way of determining whether f returns > an invisible result or not? > > Thus we want this: > > f <- function(x) x > g <- function(x) invisible(x) > >> F(f, 1) > 2 > >> F(g, 1)
I don't think there's a way to do that. Internally there's a global flag called R_Visible; if it is set to zero, the value won't print. But it gets reset to 1 very easily (e.g. by adding 1 to the result of an invisible function), and it's not available in the API for you to write C code to look at it. I think you'll just have to do require the user of your F to tell you that they want the result to be invisible. Duncan Murdoch ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
