sys.function(0)
Dunno, really. Some strange things can happen with nonstandard evaluation, like having a function designed to evaluate something in the parent of its caller, but nonetheless sometimes being called from the command line. So things are sometimes defensively coded. -pd
On 28 Mar 2016, at 00:08 , Mick Jordan <mick.jordan at oracle.com> wrote: A related question is why are sys.parent/parent.frame so permissive in their error checking? E.g:
sys.parent(-1)
[1] 0
sys.parent(-2)
[1] 0
sys.parent(1)
[1] 0
sys.parent(2)
[1] 0
parent.frame(4)
<environment: R_GlobalEnv>
Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Office: A 4.23 Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com