On 01/16/2005 03:11 PM, Larry Evans wrote: [snip]
Second of all, by itself, of course the **result of invoking inherit_linearly** shown on that page is less capable than tuple, because there's no convenient access function like get<> provided.
Yes, but since the difficulty of element access is mentioned, and no easy solution provided, and since the book is about solution's provided by mpl, and since other book sections pose problems and then provide solutions, it's only natural for the reader to assume a solution is either impossible or very difficult; yet, get_ith_head_test.cpp demonstrates that it's neither. The only change involves using inherit_head_tail instead of inherit and defining get_ith_tail, which, as you say, is not particularly original; hence, the method used by get_ith_tail should be at least mentioned as a solution to the problem.
I apologize for that last sentence. It sounds imperative. I just should have said, "the reader would have expected a solution such as...". I should also admit that maybe my impressions were influenced by what I had been doing at the time, which involved the indexed_type's library. It provides a similar get element member function but uses a more direct method because the supertypes are all the same except for the index. I couldn't figure out a different method and when I read p. 191 I just got the impression that it wasn't possible, which obviously is not what the page says. I apologize for my tone and thanks to Aleksey and you for a great book. Regards, Larry