Niels Dekker - address until 2010-10-10 wrote:
Can anybody please have a look at the following feature request by Edward Diener? https://svn.boost.org/trac/boost/ticket/3472 He proposed to add an explicit constructor, value_initialized(T const&), to boost::value_initialized<T>. This constructor would copy the value of its argument to the object held by value_initialized<T>.
When such a constructor would be added, an object held by value_initialized<T> might no longer be value-initialized. Instead it might be direct-initialized. Does anybody have any moral (?) objections against the idea that value_initialized<T> might hold a non-value-initialized object?
Personally I think it would be useful to allow the wrapped object to be direct-initialized. But I do think there's a small risk that the new explicit constructor might cause ambiguities in legacy user code. Therefor I suggested adding an extra "tag" parameter to the new constructor, of a new type, boost::direct_initialized_t:
struct direct_initialized_t { }; value_initialized(T const&, direct_initialized_t)
Does anyone else also think that's a good idea? Or does anyone prefer the explicit value_initialized(T const&) constructor originally proposed by Edward?
See also the thread starting at: "Re: [boost] Transfer of Maintenance Rights (utility/value_init)" http://lists.boost.org/Archives/boost/2010/03/164125.php
Kind regards,
Niels
Is defining a new template class (e.g., value_or_direct_initialized<T>, or whatever) out of the question? Just a suggestion, and not confident it's a good one... - Jeff