Wow! That's great. Thanks. spencer Thomas Lumley wrote:
> On Fri, 2 Sep 2005, Spencer Graves wrote: > >> Permit a mild protest on the word "appropriate" in this >> context. The >> global assignment operator "<<-" provides, for my tastes, excessive >> opportunities for problems. If I define "x" someplace else and then >> call your function, it may change my "x" in ways that generate >> considerable wailing and gnashing of teeth. > > > No, no, no. > > The sensible and appropriate uses of <<- involve modifying a variable > that already exists in the lexical parent environment. In these cases > it can't escape and ravage the calling environment. > > Certainly using <<- to assign to the calling environment is bogus. In > addition to your complaints, it doesn't even work (except from the > global environment), since <<- searches the lexical stack rather than > the call stack. > > In R, <<- can be used safely to maintain state inside a function or > shared between a set of functions (as in demo(scoping), or > demo(tkdensity)). In S-PLUS it is admittedly harder to come up with good > uses. > > -thomas -- Spencer Graves, PhD Senior Development Engineer PDF Solutions, Inc. 333 West San Carlos Street Suite 700 San Jose, CA 95110, USA [EMAIL PROTECTED] www.pdf.com <http://www.pdf.com> Tel: 408-938-4420 Fax: 408-280-7915 ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
