debugging

# Error on purpose in line 31-36. Testscript for learning debugging using different options.
imsbasics::clc()

f1 <- function(a) {
  # message("Message f1")
  b <- 10
  return(a + 1)
}


f2 <- function(a) {
  # message("Message f2")
  c <- 100
  return(a + 2)
}


f3 <- function(a) {
  # message("Message f3")
  d <- 100
  return(a + 20)
}


f4 <- function(a) {
  # browser() # ............................... If you know where the error occurs
  # message("Message f4")
  const <- "hurz"
  d <- 1000
  # a <- f3(a)
  if (a < 0) {
    a = const
  } else {
    a = const
  }
  res <- a + 3
  return(res)
}


read.csv2 <- function(file, ...) { # From Hadley...
  tryCatch(read.csv(file, ...), error = function(c) {
    c$message <- paste0(c$message, " (in ", file, ")")
    stop(c)
  })
}
# read.csv("code/dummy.csv")
# read.csv2("code/dummy.csv")

old <- getOption("error")
# options(error = NULL) 

# # used traceback to figure out where in the call stack an error occurred
# options(error = traceback)

# browse the environment in the current function call. Not possible to step back / up in hierarchy
options(error = browser)

# # use recover if you want to poke around in the environments for previous function calls.
# # In other words, you may want to \jump up to a higher level in the function call stack.
# options(error = recover)


# c <- f1(f4(f3(f2(f1(3))))) # ... Not continued in case of error. Thus, d unknown!
c <- try(f1(f4(f3(f2(f1(3)))))) # ... Continue in case of error. Thus, d = T!
# c <- tryCatch(f1(f4(f3(f2(f1(3))))), # ... Not continued in case of error. Thus, d unknown! But better error message!
#   error = function(c) {
#   c$message <- paste0(c$message, ": !!!your place for information!!!")
#   stop(c)
#   })

d <- T

options(error = old)