On Thu, 21 Jan 2010 12:20:59 -0600, Niels Dekker - address until 2010-10-10 <niels_address_until_2010-10-10@xs4all.nl> wrote:
Peter Foelsche wrote:
I'm only concerned with boost::mpl::for_each This function calls a function object by passing an object of the matching type. The contents of this object usually do not matter -- and in case they do, the programmer can write a default constructor to initialize this object. So there is no need in boost::mpl::for_each to call value_initialized.
So you think the issue can be resolved properly, merely by modifying mpl/for_each.hpp, right? You proposed at http://lists.boost.org/Archives/boost/2009/09/155805.php to modify mpl/for_each.hpp by changing:
! value_initialized<arg> x; ! aux::unwrap(f, 0)(boost::get(x));
Into:
! aux::unwrap(f, 0)(arg());
I see some subtle differences here. First of all, boost::get(x) return a reference to an lvalue, while arg() is an rvalue.
It would also break for_each iteration over a sequence of array types, although admittedly that one is likely to be written as mpl::for_each< array_types,mpl::make_identity<mpl::_1> >( ... ); Hmm, may be I should just go forward with the patch. -- Aleksey Gurtovoy MetaCommunications Engineering