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4371 :: maybe this dynamic try is not possible?

• oyster (orginal) [2018-11-09T16:28:17+01:00] view original

  In my function to make wFont for https://khchen.github.io/wNim/, the following 2 can work

  import wNim
  
  proc makeFont1(fontMessage: int): wFont {.discardable.}=
      var
          fontTmpMessage: wFont = Font(12, weight=wFontWeightBold)
      
      echo fontMessage is float
      echo fontMessage is int
      echo fontMessage is wFont
      
      if (fontMessage is float) or (fontMessage is int) :
          echo "in if"
          fontTmpMessage = Font(float fontMessage, weight=wFontWeightBold)
      
      return fontTmpMessage
  
  
  proc makeFont2(fontMessage:wFont): wFont {.discardable.}=
      var
          fontTmpMessage: wFont = Font(12, weight=wFontWeightBold)
      
      echo fontMessage is float
      echo fontMessage is int
      echo fontMessage is wFont
      
      if (fontMessage is wFont):
          echo "in if"
          fontTmpMessage = fontMessage
      
      return fontTmpMessage
  
  
  echo makeFont1(20).getPointSize()
  echo "\n"
  
  echo makeFont2(Font(32, weight=wFontWeightBold)).getPointSize()
  echo "\n"
  Run

  But when I try to combine the above into one in which the argument can be a number of the font size, or wFont.

  import wNim
  
  proc makeFont3(fontMessage: int|wFont): wFont {.discardable.}=
      var
          fontTmpMessage: wFont = Font(12, weight=wFontWeightBold)
      
      echo fontMessage is float
      echo fontMessage is int
      echo fontMessage is wFont
      
      if (fontMessage is float) or (fontMessage is int) :
          fontTmpMessage = Font(float fontMessage, weight=wFontWeightBold)
      else:
          fontTmpMessage = fontMessage
  
  echo makeFont3(40).getPointSize()
  echo "\n"
  
  echo makeFont3(Font(45, weight=wFontWeightBold)).getPointSize()
  echo "\n"
  Run

  says

  
  b2.nim(16, 15) template/generic instantiation of `makeFont3` from here
  b2.nim(14, 24) Error: type mismatch: got <int> but expected 'wFont = ref wFont:ObjectType'
  
  Run

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• Ward (orginal) [2018-11-09T16:44:45+01:00] view original

  Use when not if (the type must know by compiler at compile time, not run time):

  proc makeFont3(fontMessage: int|wFont): wFont {.discardable.}=
      var
          fontTmpMessage: wFont = Font(12, weight=wFontWeightBold)
      
      when (fontMessage is float) or (fontMessage is int) :
          fontTmpMessage = Font(float fontMessage, weight=wFontWeightBold)
      else:
          fontTmpMessage = fontMessage
      
      return fontTmpMessage
  Run

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• oyster (orginal) [2018-11-10T01:34:56+01:00] view original

  blush this is the 2nd time that I met and asked the same question these days. There is a long way for me to get familiar with Nim from a Python user view-of-point.

  thanks again

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