[Rd] codetools: Suggestion to detect potentially unassigned variables

Henrik Bengtsson hb at stat.berkeley.edu
Tue Jun 1 20:41:38 CEST 2010

This is just a note/wishlist/for the record:


foo1 <- function() {

foo2 <- function() {
  for (i in c()) res <- 1;

foo3 <- function() {
  while (FALSE) res <- 1;

foo4 <- function() {
  if (FALSE) res <- 1;

we get:

> foo1()
Error in foo1() : object 'res' not found
> foo2()
Error in foo2() : object 'res' not found
> foo3()
Error in foo3() : object 'res' not found
> foo4()
Error in foo4() : object 'res' not found

Running R CMD check on R v2.11.1pat we get:

* checking R code for possible problems ... NOTE
foo1: no visible binding for global variable 'res'

An improvement would be to also report that:

foo2: variable 'res' may not be assigned
foo3: variable 'res' may not be assigned
foo4: variable 'res' may not be assigned


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