Re: Help getting this macro to work in a for loop

[solo989]

try this: 
    
    
    import macros
    
    proc replaceSymAndIdent(a : NimNode, b : NimNode, c : NimNode, isLit : 
static[bool] = true) =
        for i in 0..len(a)-1:
          if a[i].kind == nnkSym:
            if ident(strVal(a[i])) == b:
              a[i] = c
          elif a[i].kind == nnkClosedSymChoice or a[i].kind == nnkOpenSymChoice:
            if ident(strVal(a[i][^1])) == b:
              a[i] = c
          elif a[i].kind == nnkIdent:
            if a[i] == b:
              a[i] = c
          elif a[i].len != 0:
            if a[i].kind == nnkDotExpr:
              when not isLit:
                if a[i][0].kind == nnkSym:
                  if ident(strVal(a[i][0])) == b:
                    a[i][0] = c
                elif a[i][0].kind == nnkClosedSymChoice or a[i][0].kind == 
nnkOpenSymChoice:
                  if ident(strVal(a[i][0][^1])) == b:
                    a[i][0] = c
                elif a[i][0].kind == nnkIdent:
                  if a[i][0] == b:
                    a[i][0] = c
            else:
              replaceSymAndIdent(a[i], b, c, isLit)
    
    macro iterateSeq(a : untyped, b : static[seq[string]], code : untyped) : 
untyped =
      let a =
        if a.kind == nnkSym:
          ident($a)
        elif a.kind == nnkClosedSymChoice or a.kind == nnkOpenSymChoice:
          ident($a[^1])
        else:
          a
      #echo type(a)
      result = newStmtList()
      for item in b:
        var newCode = code.copy()
        replaceSymAndIdent(newCode, a, newLit(item), isLit = true)
        result.add(newCode)
      #echo treeRepr result
      #echo repr result
      #echo ""
      #result = newStmtList()
    
    macro assignField*(obj, fieldName, value: typed) : untyped =
      let fieldSym = newIdentNode($`fieldName`)
      result = quote do:
        `obj`.`fieldSym`=`value`
    
    type
      SomeObj* = object
        a* : int
        b* : int
        c* : int
    
    var
      foo = SomeObj()
    
    iterateSeq(field, @["a", "c"]):
      assignField(foo, field, 50)
    
    echo foo
    
    assignField(foo, "a", 100)
    assignField(foo, "c", 200)
    
    block:
      assignField(foo, "b", 300)
    
    echo foo
    
    
    Run

Also, I noticed you were missing a return type on your macro so I don't know 
how your code compiled at all.