On 01/20/2006 10:00 AM, David Abrahams wrote: [snip]
I hope you're reusing the visitor mechanism provided by the signals library for function detection: http://www.boost.org/doc/html/signals/s05.html#id2739308
From looking at: template<typename V> void visit_each(V& v, const tracking_bridge& t, int) { v(t); v(t.sig); } in $BOOST_ROOT/libs/signals/test/random_signal_system.cpp, I realized the meaning of: a visit_each overload must be supplied for each object type. in http://www.boost.org/doc/html/visit_each.html, i.e. the user must explicitly call v(x) for each subobject, x, of T. However, the phrase, 'for each subobject' in visit_each.html is not really accurate since there is the subobject: minstd_rand& tracked_bridge::rand_gen; in tracking_bridge. Maybe "subobjects selected by user in the user's specialization of visit_each" would be more accurate. Anyway, the essential difference is that with visit_each, the user has to know which subobjects to visit and has to explicitly code the visit. OTOH, with fields_visitor, the user can select the object by "declaring" it visitable by wrapping it in something derived from registrar_heirarchy. The visit_each method is less intrusive (no need to modify the class to be visited), but more work. The following code: http://tinyurl.com/dx7rs demonstrates how fields_visitor can be used to emulate a visit_each method. The other example program, simple_*.cpp, shows how to do it just using fields_visitor. FYI, the preliminary fields_visitor users_guide in the vault has been updated. -best regards & thanks for the interest, Larry