[Rd] codetools: Suggestion to detect potentially unassigned variables

From: Henrik Bengtsson <hb_at_stat.berkeley.edu>
Date: Tue, 01 Jun 2010 20:41:38 +0200


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

With

foo1 <- function() {
  res;
}

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

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

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

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:

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

/Henrik



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