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2602 :: Understanding dynamic binding behavior in static blocks

• gneu (orginal) [2016-11-02T11:52:40+01:00] view original

  Given the following code:

  type
    MyType = ref object of RootObj
      testInt: int
  
  proc intSumStatic(x,y: MyType): int =
    x.testInt + y.testInt
  
  method intSumDynamic(x,y: MyType): int {.base.} =
    x.testInt + y.testInt
  
  static:
    var x = MyType(testInt: 5)
    var y = MyType(testInt: 3)
    echo "compiletime static proc   : " & $x.intSumStatic(y)
    echo "compiletime dynamic method: " & $x.intSumDynamic(y)
  Run

  , the output when compiling is:

  
  compiletime static proc   : 8
  compiletime dynamic method: 0
  
  Run

  I understand that it makes no sense to call a method at compile time, but shouldn't I expect a "cannot evaluate at compile time" error then?

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• gneu (orginal) [2016-11-02T15:04:24+01:00] view original

  Just as info for other Nim-novices like me: It is even possible to call a method at compile time, using procCall and explicitly casting to the desired type. In my given example, it could be done like so:

  echo "compiletime procCall      : " & $(procCall MyType(x).intSumDynamic(MyType(y)))
  Run

  This is awesome, because it solves the original problem I was puzzling with while I encountered the behavior described in my initial post.

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