Thanks to the nice examples shown on the ?dump.frames help page and to the
design of R, one can devise an error handling strategy when R is called
non-interactively to return run-time error information to a calling program
(e.g. CGI with Perl as the calling program).
So if I run R 1.6.2 under Linux with something like "R --vanilla --silent
<
inputfile > outputfile" where no .RData has been previously created, and
there is an execution error, is it correct that:
1) The object .Traceback will not be created and thus a traceback() call
included in an options("error") custom redefinition will always yield
the
message "No traceback available?"
The more important second question for me comes from the following: Let us
say that I use dump.frames() in the custom error handler and create a
"last.dump" object of class "dump.frames". Then debugger()
shows that
names(last.dump) will output a list of available environments to browse.
2) Are the descriptive lines produced by names(last.dump) essentially the
same content that traceback() would give in the analogous *interactive*
execution of the same code?
A code snippet example is below.
Thanks very much in advance,
Bill
Code example:
cmdline.errorhandler <- function() {
dump.frames(to.file=FALSE)
sink("results.Rerror")
## next 7 lines copied directly from debugger() body
if (length(msg <- attr(last.dump, "error.message"))) {
cat("Message: ", msg, "\n")
}
n <- length(last.dump)
calls <- names(last.dump)
cat("Available environments had calls:\n")
cat(paste(1:n, ": ", calls, sep = ""), sep =
"\n")
##
traceback() ## does not seem to find a .Traceback object
sink()
save.image() ## saves last current state
invisible()
}
options(error = quote({cmdline.errorhandler(); q()}))
----------------------------------------
Bill Pikounis, Ph.D.
Biometrics Research Department
Merck Research Laboratories
PO Box 2000, MailDrop RY84-16
126 E. Lincoln Avenue
Rahway, New Jersey 07065-0900
USA
v_bill_pikounis at merck.com
Phone: 732 594 3913
Fax: 732 594 1565
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