Lars Viklund wrote:

Are you sure you're not misunderstanding what your implementation does? VC10 and GCC 4.4.5 makes (rightfully so) a 1-tuple with an element of type pair when invoking make_tuple with a pair.

What I mean is this: #include void trigger (::std:: pair < int, int > const &p) { ::boost:: get < 0 > (::boost:: tuple < int, int > (p)) == p. first; } error: no matching function for call to ‘boost::tuples::tuple::tuple(const std::pair&)’ Compare: #include void trigger (::std:: pair < int, int > const &p) { ::std:: tr1:: get < 0 > (::std:: tr1:: tuple < int, int > (p)) == p. first; } I guess this, and Joel’s comment about boost fusion, means boost tuple should be deprecated. Chris

On 10/6/2011 3:07 AM, Krzysztof Żelechowski wrote:

Krzysztof Żelechowski wrote:

...

How come a tuple, being a generalisation of a pair, cannot be constructed from one?

I mean something along the lines

make_tuple (pair const &p) { return make_tuple (p.first, p_second); }

Would be good to have.

It turns out that TR1 supports constructing a tuple directly from a pair, so Boost should catch up.

Boost, is at the forefront of C++ dev and in fact spearheaded the development of many std libraries, including tuple. FYI, there's a more powerful tuples library called boost.fusion that includes a (simple) TR1 tuple implementation. Here's how you do it in fusion: #include #include #include <iostream> int main() { using boost::fusion::tuple; using std::pair; pair p(1, 2); tuple t = p; std::cout << t << std::endl; return 0; } But fusion gives you more than that and beyond TR1. It's the unification of all kinds of "tuples" you can imagine. For example: #include #include #include #include #include <iostream> int main() { // fusion vector is TR1 tuples in steroids using boost::fusion::vector; using boost::array; array p = { 1, 2 }; vector t = p; std::cout << t << std::endl; return 0; } Or how about: #include #include #include #include <iostream> // user defined struct struct my_struct { int a; int b; }; BOOST_FUSION_ADAPT_STRUCT(my_struct, (int, a) (int, b) ); int main() { // fusion vector is TR1 tuples in steroids using boost::fusion::vector; my_struct p = { 1, 2 }; vector t = p; std::cout << t << std::endl; return 0; } See http://tinyurl.com/3tx6kys for more. Regards, -- Joel de Guzman http://www.boostpro.com http://boost-spirit.com