Printing stack trace and continuing after error occurs in R

Question

I'm writing some R code that calls other code that may fail. If it does, I want to print a stack trace (to track down what went wrong), then carry on regardless. However, the traceback() function only provides information about uncaught exceptions. I can get the result I want via a rather complex, natty construction involving tryCatch and dump.frames, but is there not an easier way of doing this?

Answer 1

I think that you will need to use tryCatch(). You can do whatever you want in the tryCatch() function, so it's not clear to me why you are viewing this as complex. Maybe post your code example?

Answer 2

Have you tried the

 options(error=recover)

setting? Chambers 'Software for Data Analysis' has some useful hints on debugging.

Answer 3

I wrote this code about a week ago to help me track down errors that come primarily from non-interactive R sessions. It's still a little rough, but it prints a stack trace and continues on. Let me know if this is useful, I'd be interested in how you would make this more informative. I'm also open into cleaner ways to get this information.

options(warn = 2, keep.source = TRUE, error = 
  quote({ 
    cat("Environment:\n", file=stderr()); 

    # TODO: setup option for dumping to a file (?)
    # Set `to.file` argument to write this to a file for post-mortem debugging    
    dump.frames();  # writes to last.dump

    #
    # Debugging in R
    #   http://www.stats.uwo.ca/faculty/murdoch/software/debuggingR/index.shtml
    #
    # Post-mortem debugging
    #   http://www.stats.uwo.ca/faculty/murdoch/software/debuggingR/pmd.shtml
    #
    # Relation functions:
    #   dump.frames
    #   recover
    # >>limitedLabels  (formatting of the dump with source/line numbers)
    #   sys.frame (and associated)
    #   traceback
    #   geterrmessage
    #
    # Output based on the debugger function definition.

    n <- length(last.dump)
    calls <- names(last.dump)
    cat(paste("  ", 1L:n, ": ", calls, sep = ""), sep = "\n", file=stderr())
    cat("\n", file=stderr())

    if (!interactive()) {
      q()
    }
  }))

PS: you might not want warn=2 (warnings converted to errors)