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1087 :: Are cstrings from imported C functions garbage collected?

• propolis (orginal) [2015-03-29T09:50:00+02:00] view original

  Given this prototype: proc test*(): cstring {.cdecl, importc: "test", dynlib: test.}

  Is the cstring returned going to be garbage collected by Nim or do I have to manually free it like in C?

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• Araq (orginal) [2015-03-29T13:12:30+02:00] view original

  Free it like in C.

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• propolis (orginal) [2015-03-29T13:33:21+02:00] view original

  Is it GC_unref()?

   var t: cstring = test()
    ...
   GC_unref(t)
  Run

  I get" Error: type mismatch: got (cstring) but expected one of: system.GC_unref(x: seq[T]) system.GC_unref(x: string) system.GC_unref(x: ref T)

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• propolis (orginal) [2015-03-29T13:58:27+02:00] view original

  To clarify, the returned cstring is a pointer: char * test()

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• Stefan_Salewski (orginal) [2015-03-29T15:13:35+02:00] view original

  You have to investigate how free() is done for your string generally when the library is used from C and then do the same. Of course C has generally no GC, so something like Nim's GC_unref() can not work with the plain C string. (Later, if you want to write a really high level Nim wrapper, you may consider more advanced interfaces, which may involve copying the string to a garbage collected Nim string and immediately freeing the C string.)

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• propolis (orginal) [2015-03-29T16:14:39+02:00] view original

  Got it. Thanks!

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