Eval and the enclos argument

On Sat, Oct 2, 2010 at 8:18 AM, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:

On 02/10/2010 7:57 AM, Hadley Wickham wrote:

Hi all,

I'm trying to understand the default value of the enclos argument of eval:

 enclos = if(is.list(envir) || is.pairlist(envir)) parent.frame()
else baseenv()

Why isn't it just

 enclos = parent.frame()

given that enclos is only meaningful (given my reading of the
documentation) when envir is not an environment already.

Hadley

I think that handles the case of envir=NULL.

So that makes eval(expr, NULL) equivalent to eval(expr, baseenv()), right?