Roland Richter <[EMAIL PROTECTED]> writes: > David A. Greene wrote: > >> The fundamental problem is that it's inconvenient to iterate through a >> tuple. All we have is the get<> template to access tuple elements. >> Iterating is again conceptually simple -- just increment an index. >> But the fact that get<> is a template implies the index must be a >> compile-time constant, meaning we need a compile-time loop (or, if >> you prefer, programmer-controlled loop unrolling) to iterate. > > Iteration through a tuple is indeed not so simple, but *recursion* > is, and you can do that at runtime. > > All you need is to get the head and the tail out of a tuple, and, > in turn construct a tuple out of head and tail. Boost.Tuple provides > that: "get_head()" and "get_tail()", although it is not mentioned > in the docs (why?). > > I'm not sure whether I completely understand what you need (did I?), > but here is how I'd do it. Anyway, the idea of "iterating" through > a tuple - and also the spanning_iterator thing - sounds interesting.
See also http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/*checkout*/boost/boost/boost/python/detail/def_helper.hpp which does some similar things, except with a compile-time criterion. -- David Abrahams [EMAIL PROTECTED] * http://www.boost-consulting.com Boost support, enhancements, training, and commercial distribution _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
