On Sun, 30 Mar 2008, Gabor Grothendieck wrote: > Also in trying it out again it seems that its not like > on.exit but more like return:
Yes -- if you can point out what in the documentation ever gave the idea it might be like on.exit then we can fix the documentation. > > 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. The documentation descriped this as a downward-only version -- that is standard terminology for a callCC that produces continuations that are no longer valid after the callCC call exits. Not sure why your original question was about "callCC in 2.7.0" -- I believe callCC was added in 2.5.0, the same time as codetools became recommended, and hasn't changed since. It is not a function every R user needs to have in their repertoire, but it can be very useful in some situations. luke > On Sun, Mar 30, 2008 at 12:34 PM, Gabor Grothendieck > <[EMAIL PROTECTED]> 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, <[EMAIL PROTECTED]> 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/ >>> >> > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > -- Luke Tierney Chair, Statistics and Actuarial Science Ralph E. Wareham Professor of Mathematical Sciences University of Iowa Phone: 319-335-3386 Department of Statistics and Fax: 319-335-3017 Actuarial Science 241 Schaeffer Hall email: [EMAIL PROTECTED] Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel