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2798 :: Should nim runtime catch signals like SIGFPE and raise an exception by default?

• mogu (orginal) [2017-02-15T02:58:42+01:00] view original

  I found lib/system/except.nim catch most signals and just print signal message then quit. Is it possible to raise an exception instead of immediately quit? This gives more choice to users I think.

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• mogu (orginal) [2017-02-15T03:37:37+01:00] view original

  I change lib/system/excpt.nim(362)

  quit(1)
  Run

  to

  raise newException(SystemError, "SystemError")
  Run

  and the following codes works

  var a: int = 0
  
  try:
    var b: int = 5 div a
    echo b
  except SystemError:
    echo "Exception: " & getCurrentExceptionMsg()
  
  echo "end"
  Run

  outputs:

  
  SIGFPE: Arithmetic error.
  Exception: SystemError
  end
  Run

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• Arrrrrrrrr (orginal) [2017-02-16T10:00:56+01:00] view original

  From excpt's source code, it was written with systems without exceptions in mind: Exception handling code. Carefully coded so that tiny programs which do not use the heap (and nor exceptions) do not include the GC or memory allocator.

  You can set a custom message however:

  errorMessageWriter = proc(m: string) = echo "Custom: ", m
  
  var i = 0
  echo 5 div i
  # Custom: Traceback (most recent call last)
  # main.nim(5)              main
  #system.nim(2534)         sysFatal
  # Error: unhandled exception: division by zero [DivByZeroError]
  Run

  It depends on what you need, you probably prefer to set a global/local exception handler:

  globalRaiseHook = proc (e: ref Exception): bool =
    echo "AY AY AY!"
    quit(1)
  
  var i = 0
  echo 5 div i
  # AY AY AY!
  # exit status 1
  Run

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