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5672 :: What does "cannot be captured as it would violate memory safety" mean?

• marks (orginal) [2019-12-11T20:10:50+01:00] view original

  In some situations I get the error message "cannot be captured as it would violate memory safety". I understand that this means nim is trying to stop me shooting myself in the foot, but is there anywhere I can read an explanation and if it is possible to do what I want without triggering this error?

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• mratsim (orginal) [2019-12-11T21:13:37+01:00] view original

  You are probably trying to use a var parameter somewhere you shouldn't like a closure.

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• marks (orginal) [2019-12-11T22:17:22+01:00] view original

  The variable is sent as a var to a proc where it works fine. But I then in that proc I pass it to another proc and in that one I get the error. I've also tried passing it to the other proc without var (since in that data is only read) but get the same error. Is there an alternative to var that would work?

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• Araq (orginal) [2019-12-12T09:00:58+01:00] view original

  You can use ptr T instead of var T then, but beware, it's unsafe. It's better to do this instead:

  proc outer(x: var string) =
    proc inner(x: var string) =
      x.add "abc"
    inner(x)
  
  var g = "x"
  outer(g)
  echo g
  Run

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