callCC in 2.7.0
Also in trying it out again it seems that its not like
on.exit but more like return:
F <- function(f) { f(10); print(2); f(20); 3}
callCC(F)
acts the same as:
F <- function() { return(10); print(2); f(20); 3}
F()
and there is no documented way to restart F
at the point it left off so I assume it can't.
On Sun, Mar 30, 2008 at 12:34 PM, Gabor Grothendieck
<ggrothendieck at gmail.com> wrote:
I think the only relationship to that is the name since it does not appear to allow one to leave a function in the middle of its processing and re-enter it back at that point -- which is what would be needed. On Sun, Mar 30, 2008 at 12:04 PM, <h.wickham at gmail.com> wrote:
Would anyone like to explain if callCC in R 2.7.0 gives anything that on.exit does not already provide? It seems that the exit condition once defined cannot be added to overridden whereas with on.exit multiple on.exit's add additional on.exits rather than being ignored. Is this important?
It facilitates a completely different style of programming - see http://en.wikipedia.org/wiki/Continuation-passing_style -- http://had.co.nz/