open_close vs keep_open.cpp

// program_start
fd_log = open("logfile.log")

fn log(msg) {
  fd_log.write(msg)
  fd_log.flush()
}

log("something happened")

// program ends and all open file descriptors are closed by the OS

##############################################

// program_start do nothing

fn log(msg) {
  // this function absolutely must be SYNC, otherwize we can end up opening the same file many times!
  fd_log = open("logfile.log")
  try {
    fd_log.write(msg); 
  } finally {
    fd_log.close()
  }
}

log("something happened")

// program ends