On Wed, 2009-03-11 at 21:46 +0800, Bo Yang wrote: This is mostly fine. A couple of comments, however: 1) I'm not entirely sure where you're going with dom_node_create() 2) I don't think that there should be a destroy() entry in the public vtable -- destruction of objects occurs implicitly when their reference count falls to zero and they're not hooked into the tree. Therefore, we don't want to give the client the possibility of screwing things up by calling the destroy() entry directly. I think we want the first two fields in dom_node_internal to be: void *vtable; void (*destroy)(...); as the destructor should be private. 3) attr_vtable needs to be static. J.