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8749 :: Bug with peekableOutputStream?

• vitreo12 (orginal) [2021-12-28T17:59:56+01:00] view original

  Hello there,

  It was my understanding that peekableOutputStream would allow to use peekLine calls on a Stream. However, the following code spits out a runtime error:

  import osproc, streams
  
  let
    process =  startProcess(
      "echo",
      args = ["HELLO"],
      options = {poUsePath, poStdErrToStdOut}
    )
  
  echo process.peekableOutputStream().peekLine()
  
  Run

  output:

  
  /home/francesco/.choosenim/toolchains/nim-1.6.0/li
  b/pure/streams.nim(1097) peekLine
  /home/francesco/.choosenim/toolchains/nim-1.6.0/li
  b/pure/streams.nim(213) getPosition
  SIGSEGV: Illegal storage access. (Attempt to read
  from nil?)
  Run

  Is this to be expected? How can I peek a line from an outputStream of a Process?

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• demotomohiro (orginal) [2021-12-29T01:54:43+01:00] view original

  Calling peekLine to peekableOutputStream() is not currently supported. peekline proc in lib/pure/streams.nim uses getPosition and setPosition proc but pipe cannot get or set read/write position.

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• vitreo12 (orginal) [2021-12-29T11:49:59+01:00] view original

  I see, thanks.

  So I can only read from the pipe but I can't "preview" what I am going to read?

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• demotomohiro (orginal) [2021-12-30T15:37:56+01:00] view original

  Procedures implemented with peekData (peekChar, peekStr, etc) should work.

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• vitreo12 (orginal) [2021-12-30T17:46:46+01:00] view original

  Thanks, I'll give that a try

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