Question

What is withCallingHandlers and how does it work?

Answer 1

withCallingHandlers works similar to tryCatch but

1. remembers the call stack down to the point where the condition was signaled
2. resumes the execution after the point where the condition was signaled

f <- function() {
  warning("deprecated function called")
  print("Hello world")
}
withCallingHandlers(f(), warning = function(w) { write.to.log(sys.calls()) })
## Warning in f(): deprecated function called
## [1] "Hello world"