"Peter Foelsche" <peter_foelsche@agilent.com> wrote in message news:h7jv3a$n4n$1@ger.gmane.org...
what is the use of value_initialized in boost::mpl::for_each? It should be sufficient if the value is initialized by the constructor. value_initialized() calls memset() in before calling the constructor. This memset() is not being optimized away with gnu-c++ 4.4.1. What class does require zeroed memory to work correctly?
i second that... ...msvc++ 8.0 and 9.0 ("with all available optimizations and maximum inlining depth") are also "unable" to remove the redundant memset() call (it is only sometimes replaced with an intrinsic implementation)... there was a somewhat related discussion ( http://lists.boost.org/Archives/boost/2004/02/61582.php ) dealing, among other things, with the problem of default construction in mpl::for_each ... in the current implementation you must either pay for default construction or pay for added verbosity/ugliness of the "wrap" approach... ...i must admit i did not quite understand the argument of Aleksey Gurtovoy that the proposed "aux::unwrap(f, 0)::operator()<arg>()" solution would "would rule out ordinary function objects" (can you even use them with mpl::for_each?) and that "it's not portable" (the ::operator()<arg>() syntax is not standard?)... (apologies if this should go to a seperate thread...it seemed related enough :) -- "That men do not learn very much from the lessons of history is the most important of all the lessons of history." Aldous Huxley