On 6 February 2022 at 18:18, Jeroen Ooms wrote:
| Well not really, this kind of misses my point that it the
| unwind-protect makes it impossible to meaningfully catch the R error
| in C++, handle it, and continue running the C++ code, without aborting
| the entire mission and throwing the user back in the console.
I see. Well if we wanted to catch an R error on the R side, adding tryCatch
still works. Here are your initial R function, renamed, and a new one:
callbackWithoutTry <- function() {
stop("Ouch from R")
}
callback <- function() {
tryCatch(stop("Ouch from R"),
error = function(e) { cat("Well that went south\n") },
finally = function(e) { cat("Normal end\n") } )
}
This (under UNWIND_PROTECT) behaves:
edd@rob:/tmp/uptest(master)$ install.r .
* installing *source* package ‘uptest’ ...
** using staged installation
** libs
rm -f uptest.so RcppExports.o callback.o
ccache g++-11 -I"/usr/share/R/include" -DNDEBUG -DRCPP_USE_UNWIND_PROTECT
-I'/usr/local/lib/R/site-library/Rcpp/include' -fpic -g -O3 -Wall -pipe
-pedantic -c RcppExports.cpp -o RcppExports.o
ccache g++-11 -I"/usr/share/R/include" -DNDEBUG -DRCPP_USE_UNWIND_PROTECT
-I'/usr/local/lib/R/site-library/Rcpp/include' -fpic -g -O3 -Wall -pipe
-pedantic -c callback.cpp -o callback.o
ccache g++-11 -Wl,-S -shared -L/usr/lib/R/lib -Wl,-Bsymbolic-functions
-flto=auto -Wl,-z,relro -o uptest.so RcppExports.o callback.o -L/usr/lib/R/lib
-lR
installing to /usr/local/lib/R/site-library/00LOCK-uptest/00new/uptest/libs
** R
** byte-compile and prepare package for lazy loading
** help
*** installing help indices
** building package indices
** testing if installed package can be loaded from temporary location
** checking absolute paths in shared objects and dynamic libraries
** testing if installed package can be loaded from final location
** testing if installed package keeps a record of temporary installation path
* DONE (uptest)
edd@rob:/tmp/uptest(master)$ R -q
> uptest::uptest()
Well that went south
[1] 42
>
So this catches the stop(), enters a designates block and resumes in the C++
function that called it all still returning the 42 we desired as The Answer.
Dirk
--
https://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org
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