On Feb 14, 2005, at 7:40 PM, Edward Diener wrote:
Howard Hinnant wrote:
On Feb 14, 2005, at 7:06 AM, John Maddock wrote:
The following simple patch to tuple_basic.hpp allows tuples to be constructed from std::pairs (there is already an assignment operator, but the copy constructor is missing for some reason, and is required for TR1 conformity).
RCS file: /cvsroot/boost/boost/boost/tuple/detail/tuple_basic.hpp,v retrieving revision 1.28 diff -r1.28 tuple_basic.hpp 627a628,636
template <class T, class U> tuple(const std::pair<T, U>& p) : inherited(p.first, p.second, detail::cnull(), detail::cnull(), detail::cnull(), detail::cnull(), detail::cnull(), detail::cnull(), detail::cnull(), detail::cnull()) { BOOST_STATIC_ASSERT(length<tuple>::value == 2);// check_length = 2 }
Is it acceptable to add this?
I think we could do better, but it would be stretching TR1 (which I think is good).
I think any compatible tuple-like type should be convertible to tuple (pair, array, maybe complex?, anything else that declares itself tuple-like and implements the tuple interface).
What is the technical definition of a tuple-like type ?
See http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2002/n1382.pdf and search for is_tuple_like. There's a nicely written compact definition. In a nutshell, it implements the tuple interface, and registers itself with the is_tuple_like trait. -Howard