How to hide or disable in-function printed message

Question

Suppose I have a function such as:

ff <- function(x) {
  cat(x, \"\\n\")
  x^2}

And run it by:

y <- ff(5)
# 5 
y
# [1         


        

Answer 1

Here's a nice function for suppressing output from cat() by Hadley Wickham:

quiet <- function(x) { 
  sink(tempfile()) 
  on.exit(sink()) 
  invisible(force(x)) 
} 

Use it like this:

y <- quiet(ff(5))

Source: http://r.789695.n4.nabble.com/Suppressing-output-e-g-from-cat-td859876.html