✨ Add pick macro for handling runtime polymorphism

src/oolib.nim

@@ -171,3 +171,10 @@ macro isInstanceOf*(v: typed, T: typedesc): bool =
     else:
       `v`.type is `T`
 
+macro pick*(t, P: untyped): tuple =
+  let tupleTy = ProtocolTable[P.strVal]
+  result = nnkTupleConstr.newTree()
+  for v in tupleTy:
+    let name = v[0]
+    result.add newColonExpr(name, t.newDotExpr(name))
+

tests/implementation.nim

@@ -36,8 +36,13 @@ class HTMLWriter impl Writer:
 
 let book = Book.new(price = 500)
 
-let _ = book.toProtocol()
-
 let diary = Diary.new(price = 300)
 
-let _ = diary.toProtocol()
+var products: seq[Product] = @[]
+
+products.add book.toProtocol().pick(Product)
+
+products.add diary.toProtocol().pick(Product)
+
+for product in products:
+  echo product.price