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6224 :: Help understanding proc()

• Pixeye (orginal) [2020-04-16T16:19:57+02:00] view original

  ## INVALID
  type
    Something = object
      act* : proc()
      name*: string
  
  var something = Something(.act : someaction)
  
  proc someaction*()=
    something.name = "boo"
  Run

  ## VALID
  type
    Something = object
      act* : proc()
      name*: string
  
  var something = Something()
  something.act = someaction
  
  proc someaction*()=
    something.name = "boo"
  Run

  ## VALID
  type
    Something = object
      act* : proc()
      name*: string
  
  var something = Something()
  something.act = someaction
  
  proc someaction*()=
    # some code without something
    discard
  Run

  Why the first example is invalid ? The error gives me undeclared identifier but I don't understand what it means since I see the identifier.

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• DeletedUser (orginal) [2020-04-16T16:36:50+02:00] view original

  You can forward declare procs to reference them before they are defined.

  type
    Something = object
      act*: proc()
      name*: string
  
  proc someaction*()
  
  var something = Something(act: someaction)
  
  proc someaction*() =
    something.name = "boo"
  Run

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• lscrd (orginal) [2020-04-16T17:56:48+02:00] view original

  Sorry, but your second example is no more valid than the first one.

  In both cases, as @Hlaaftana said, you need to declare the proc before referencing it.

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