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1889 :: How do I get the value of a constant symbol within a macro?

• Krux02 (orginal) [2015-12-23T14:16:23+01:00] view original

  let's say the node of the argument is typed, and I know it is const, so a macros.getImpl does work

  const banana = join(["bana", "na"])
  
  
  proc foo(arg:string): int = 0
  
  macro foobar(arg: typed): stmt =
    # it's not the root node I am working on.
    let subNode = arg[1]
    echo subNode.treeRepr     # Sym "banana"
    echo subNode.getType.repr # string
    echo subNode.strVal       # Error: field 'strVal' cannot be found
    
    let sym = subNode.symbol
    echo sym.repr             # banana
    echo sym.kind             # Error: type mismatch: got (NimSym), expected macros.kind(n: NimNode)
    echo sym.strVal           # Error: type mismatch: got (NimSym), expected macros.strVal(n: NimNode)
  
  
  foobar(foo(banana))
  Run

  I could implement my own eval that works on the const implementation, but I hope I do not need to eval something that the compiler already has evaluated for me at that time.

  EDIT:

  I found a solution. For some reason, getImpl doesn't get me the tree in the const declaration, but a string literal. Which I think I pretty weired, because It doesn't represent the AST in any way. But at least I can use it to get the string value of my symbol. So this is my solution:

  macro foobar(arg: typed): stmt =
    let subNode = arg[1]
    echo subNode.symbol.getImpl.strVal
  Run

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