unexpected behaviour when defining a function

bar <- function() 1
foo <- function(bar. = bar()) {

foo()

foo(bar = bar)

You can't have x=x in an argument list.

Try the following noting that we put a dot at the end of bar:

bar <- function() 1
foo <- function(bar. = bar()) {

+      bar
+ }

foo()

function() 1

foo(bar = bar)

function() 1

On 9/11/06, Deepayan Sarkar <deepayan.sarkar at gmail.com> wrote:

Hi,

I know S manuals used to warn against using the same names for a
variable and a function, but I have never seen that cause problems in
R, so I usually don't pay much attention to it. Which is why the
following behaviour came as a surprise:

bar <- function() 1
foo <- function(bar = bar()) {

+     bar
+ }

foo(9)

[1] 9

foo()

Error in foo() : recursive default argument reference

Exactly what rule am I violating here?

The following gives a slightly different error, but I assume it has a
similar origin:

bar <- function() 1
foo <- function(bar) {
   if (missing(bar)) bar <- bar()
   bar
}
foo()

This version works fine though (so the rule probably involves function
arguments somehow):

foo <- function(baz) {
   if (missing(baz)) {
       baz <- function() 2
       baz <- baz()
   }
   baz
}
foo()

-Deepayan