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3792 :: Guessing the module -- works, but is there a even better way?

• Stefan_Salewski (orginal) [2018-04-30T23:46:05+02:00] view original

  [EDIT] Well, does not even work correctly, expected result would be "times.DateTime". "When compiles()" give the same.

  import times, macros
  
  macro m(o: typed): untyped =
    #let ot = getType(o)
    let oti = getTypeInst(o)
    #let s1 = $ot.toStrLit
    let s2 = $oti.toStrLit
    
    #echo s1
    echo s2
    if compiles("var h:" & "tables." & s2):
      echo "tables." & s2
    elif  compiles("var h:" & "times." & s2):
      echo "times." & s2
  
  var x: times.DateTime
  
  m(x)
  Run

  
  DateTime
  tables.DateTime
  
  Run

  Why I may need the module? Well, some months ago someone asked if we can use GtkBuilder with gintro. Answer is yes of course, but to make it typesafe we would have to create a macro which tests type of result from Builder.getObject(). In most cases module will be gtk, but not always. For example, if we pass a var of type Button, we would have to check if result returned by Builder.getObject() is GtkButton. (https://developer.gnome.org/gtk3/stable/ch01s03.html)

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• DeletedUser (orginal) [2018-05-01T01:08:53+02:00] view original

  compiles takes an expression argument, not a string argument. I myself don't know a way to do this other than to do something like:

  import macros, times, tables
  
  macro m(o: typed): untyped =
    let oti = getTypeInst(o)
    let s2 = oti.toStrLit.strVal
    let s2ident = newIdentNode(s2)
    
    echo s2
    result = quote do:
      when declared(tables.`s2ident`):
        static: echo "tables.", `s2`
      elif declared(times.`s2ident`):
        static: echo "times.", `s2`
  
  var x: times.DateTime
  
  m(x)
  Run

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