On 3/14/06, Gabor Grothendieck <[EMAIL PROTECTED]> wrote:
> I would very much like to see such a feature too.
>
> On 3/14/06, Henrik Bengtsson <[EMAIL PROTECTED]> wrote:
[snip]
> > A nicer and more general solution is to have a subclass "simpleExit"
> > of "simpleCondition" and make source() catch such signals via
> > tryCatch(..., simpleExit=function(se) {...}). Here is a complete
> > example:
> >
> > simpleExit <- function(...) {
> > cond <- simpleCondition(...)
> > class(cond) <- c("simpleExit", class(cond))
> > cond
> > }
> >
> > exit <- function(...) {
> > invisible(signalCondition(simpleExit(...)))
> > }
> >
> > evalWithExit <- function(...) {
> > tryCatch(..., simpleExit=function(cond) cond)
> > }
> >
> > sourceWithExit <- function(...) {
> > evalWithExit(source(...))
> > }
> >
> >
> > Examples:
> >
> > > evalWithExit({cat("Hi\n");exit("Bye!");cat("there\n")}); cat("bye\n")
> > Hi
> > <simpleExit: Bye!>
> > bye
> >
> > # Compare this...
> > > code <- 'cat("Hi\n"); exit("Bye!"); cat("there\n")'
> > > source(textConnection(code))
> > Hi
> > there
> >
> > # ...with this:
> > > sourceWithExit(textConnection(code))
> > Hi
> > <simpleExit: Bye!>
> >
> > R-core, would this be a useful feature to add to source()?
> >
> > /Henrik
I just realized that I just might be looking for a way to generate a
user-interrupt signal, e.g. (try pressing Ctrl-C or Ctrl-Break)
tryCatch(Sys.sleep(10), interrupt=function(intr) print(intr))
A caught "interrupt" object looks like:
list()
- attr(*, "class")= chr [1:2] "interrupt" "condition"
So, trying:
simpleInterrupt <- function(...) {
cond <- simpleCondition(...)
class(cond) <- c("simpleInterrupt", "interrupt", class(cond))
cond
}
interrupt <- function(...) {
invisible(signalCondition(simpleInterrupt(...)))
}
Unfortunately that is not enough; the interrupt seems not to be
signalled. Same holds if you try to "resignal" a caught interrupt,
e.g. (try pressing Ctrl-C or Ctrl-Break *once*):
tryCatch({
tryCatch({
print(1)
Sys.sleep(10)
print(2)
}, interrupt=function(intr) {
cat("User-interrupt signal caught\n")
signalCondition(intr)
})
Sys.sleep(10)
print(3)
})
gives:
[1] 1
User-interrupt signal caught
<a 10 second sleep>
[1] 3
I was hoping that the *resignaled* user-interrupt signal would break
out of the out outer tryCatch too.
So, I guess, now my question is, is it possible to generate a
low-level user-interrupt signal from source code? That would be
useful.
Thanks
Henrik
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