Mirror of forum.nim-lang.org

5254 :: Getting a strange error with file streams

• dotheda (orginal) [2019-10-01T05:15:06+02:00] view original

  First off, not even sure if the code will really work once I fix this, but I'm sure I can figure out the rest;

  proc get_file_data(file: FileStream, offset: int, size: int): seq[char] =
      var test = newSeq[char]()
      file.setPosition()
      
      for i in offset .. (size - 1):
          var x: char
          file.setPosition(i)
          discard file.readData(x.addr, 1)
          result.add(x)
      
      test
  Run

  returns the error

  
  main.nim(32, 9) Error: type mismatch: got <FileStream>
  but expected one of:
  proc setPosition(s: Stream; pos: int)
  
  expression: setPosition(file)
  Run

  I'm not sure what type I'm supposed to be using? I've tried Stream as well. Maybe there's a more elegant way to do this as well? Not sure.

---

• Stefan_Salewski (orginal) [2019-10-01T08:10:00+02:00] view original

  Compiler message is very clear. There is only proc setPosition(s: Stream; pos: int) which takes an non optional int as second parameter. So call file.setPosition() is invalid. I have no idea what you wants to do exactly, maybe you assume that there is a default parameter to setPosition()? There is none in this case, so maybe use file.setPosition(0). See https://nim-lang.org/docs/lib.html

---

• dotheda (orginal) [2019-10-01T20:52:46+02:00] view original

  Ah, I'm an idiot. Thank you.

---

• Araq (orginal) [2019-10-01T21:17:05+02:00] view original

  Also watch out, you use test and result inconsistently. (There is no need for test.)

---