On Tue, Nov 23, 2010 at 12:05 PM, Hossein Haeri <powerprogman@yahoo.com> wrote:

Dear all,

Is there any function in Boost.Tuple which works like this for n-tuples for any given n?

template<typename T1, typename T2, typename T3>
tuples::tuple<T1, T2, T3> augment_tuple(tuples::tuple<T1, T2> tup, T3 t3)
{
return tuples::make_tuple(tup.get<0>(), tup.get<1>(), t3);
}

(Obviously, here n == 2.) The purpose of this augment_tuple (or, patch, or whatever) is to take an n-tuple and a new element and patch the new element to the end of the n-tuple in order to get a (n + 1)-tuple. Repetitive code which can produce enough overloads for a large enough n is of course trivial. I'm wondering whether MPL has a utility which can automated this though?

I think this is what you need. Since Boost.Tuple can be a conforming ForwardSequence (with the appropriate header),
this does exactly what you want.

http://www.boost.org/doc/libs/1_43_0/libs/fusion/doc/html/fusion/algorithm/transformation/functions/push_back.html

- Rob.