Mirror of forum.nim-lang.org

8367 :: using readFile at compile time break exceptions

• giaco (orginal) [2021-08-25T20:34:08+02:00] view original

  I know that there's also macros.staticRead, but I was puzzled by this behavior. Is this a bug?

  https://play.nim-lang.org/#ix=3wWE

  proc f() =
    try:
      discard "FAILME".readFile
    except:
      echo "unreached"
  
  static:
    f()
  Run

  Expected output

  
  unreached
  Run

  Actual output

  
  ....io.nim(849)              readFile
  Error: unhandled exception: cannot open: FAILME [IOError]
  Run

---

• Araq (orginal) [2021-08-26T08:11:43+02:00] view original

  Sorry, but why does this matter? If you need the file at compile-time, require that it exists, don't catch an exception and do something else instead, this results in builds that nobody should have to maintain.

---

• PMunch (orginal) [2021-08-26T08:54:37+02:00] view original

  Sure, but just because it might be a bad idea doesn't mean that it shouldn't work. And how do we know this is only related to this exception?

---

• Stefan_Salewski (orginal) [2021-08-26T09:03:38+02:00] view original

  I was not even aware that exceptions can work at compile-time at all, but then found yesterday this old thread

  https://forum.nim-lang.org/t/625#3389

  I think I have to read that thread to get an idea what compile-time exceptions can do for me :-)

---

• giaco (orginal) [2021-08-26T11:21:32+02:00] view original

  I don't understand tour point. It seems perfectly legit to me using try/except to readFile at compile time. For example, i know file can be in two locations, so I try first and then second.

  The point here is that this specific exception is not catched (according to given error) event if exceptions generally works at compile time (see linked example)

---

• timothee (orginal) [2021-08-26T22:39:51+02:00] view original

  This is precisely what https://github.com/nim-lang/Nim/pull/13714 would fix.

---

• giaco (orginal) [2021-08-26T22:44:41+02:00] view original

  Now I understand where the friction lies

---