next steps for closure iterators

tests/objects/tobjconstr.nim

@@ -0,0 +1,41 @@
+discard """
+  output: '''(k: kindA, a: (x: abc, z: [1, 1, 3]), empty: ())
+(k: kindA, a: (x: abc, z: [1, 2, 3]), empty: ())
+(k: kindA, a: (x: abc, z: [1, 3, 3]), empty: ())
+(k: kindA, a: (x: abc, z: [1, 4, 3]), empty: ())
+(k: kindA, a: (x: abc, z: [1, 5, 3]), empty: ())
+(k: kindA, a: (x: abc, z: [1, 6, 3]), empty: ())
+(k: kindA, a: (x: abc, z: [1, 7, 3]), empty: ())
+(k: kindA, a: (x: abc, z: [1, 8, 3]), empty: ())
+(k: kindA, a: (x: abc, z: [1, 9, 3]), empty: ())
+(k: kindA, a: (x: abc, z: [1, 10, 3]), empty: ())'''
+"""
+
+type
+  TArg = object
+    x: string
+    z: seq[int]
+  TKind = enum kindXY, kindA
+  TEmpty = object
+  TDummy = ref object
+    case k: TKind
+    of kindXY: x, y: int
+    of kindA: 
+      a: TArg
+      empty: TEmpty
+
+proc `$`[T](s: seq[T]): string =
+  # XXX why is that not in the stdlib?
+  result = "["
+  for i, x in s:
+    if i > 0: result.add(", ")
+    result.add($x)
+  result.add("]")
+
+proc main() =
+  for i in 1..10:
+    let d = TDummy(k: kindA, a: TArg(x: "abc", z: @[1,i,3]), empty: TEmpty())
+    echo d[]
+
+main()
+