unexpected behavior of the "of" operator

[AdrianV]

I think this should compile, but it does not:

type
  TPerson = object of TObject
    name*: string   
    age: int        

  TStudent = object of TPerson
    id: int                   

var
  student: TStudent
  person: TPerson


echo student of TStudent # is true
echo student of TPerson # does not compile, should be true, throws Error: 'TStudent' can never be of this subtype

[AdrianV]

this code refuses to compile, but should IMHO - aborts with:
Error: type mismatch: got (PKeysIterator[string, int], PBtree[string, int])
but expected one of:
initIterator(it: PTreeIterator[T, D], n: PBtree[T, D])
since PKeysIterator[string, int] is a PTreeIterator[string, int] I can't see anything wrong here

I guess the problem is related to the "of" problem , therefore I don't open a new issue:

type
  PBtree* [T,D] = ref TBTree[T,D]
  TItem* [T,D] = object
        key* : T
        value* : D
        node: PBtree[T,D]
        when not (D is string):
          val_set: Bool

  TItems[T,D] = seq[ref TItem[T,D]]
  TBTree* [T,D] = object
        slots: TItems[T,D]
        left: PBtree[T,D]
        count: Int32

  RPath[T,D] = tuple[
    Xi: Int,
    Nd: PBtree[T,D] ]

  PTreeIterator* [T,D] = ref TTreeIterator[T,D]
  TTreeIterator* [T,D] = object 
    path: array[0..30, RPath[T,D]]
    level: int
    current: ref TItem[T,D]

  PKeysIterator* [T,D] = ref TKeysIterator [T,D]  
  TKeysIterator* [T,D] = object of TTreeIterator[T,D]

proc initIterator [T,D] (it: PTreeIterator[T,D], n: PBtree[T,D]) {.inline.} = 
  it.Path[0].Nd = n
  it.Path[0].Xi = -1

proc keys* [T,D](n: PBtree[T,D]): PKeysIterator[T,D] = 
  new(result)
  initIterator(result, n)

var 
  root: PBTree[string, int]
  iter = keys(root)

[Araq]

Sigh ... See bug #88 ...

[AdrianV]

sorry for double posting - I haven't seen the other issue. Currently a cast helps in the second example.