Hi all, the following is just a curiosity of mine, about which I would like to get some comment. On browsing a few discussions about generic tree libraries, I got the impression that many people judge that pre-/in-/post-order iterators, and alike, are essential in any tree class or container (concept). My opinion is that a generic tree class (I refrain from calling it a "container", because in my mind a tree does not necessarily model a Container concept) should be designed much more after the BGL than after the STL containers. One design choice in the BGL is that there are "visitor" functions, e.g. breadth_first_search() and depth_first_search(), but there are no "bfs_iterator" or "dfs_iterator". What are the motivations that lead to such choice? Might they be applied to trees as well? As a simple example in favor of the former approach, a "BGL-like" tree data structure would allow a user to use a std::vector as a heap (by overloading the suitable functions). I know that for the SoC several tree libraries have been proposed. Is there no room or interest for other proposals any longer? Is it possible to take a look at those proposals? Regards Nicola