Re: [Boost-users] a tuple from a pair?

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To: boost-users@lists.boost.org From: giecrilj@stegny.2a.pl Date: Fri, 7 Oct 2011 11:18:24 +0200 Subject: Re: [Boost-users] a tuple from a pair?

Lars Viklund wrote:

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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

If you use boost::fusion::at_c<0> rather than std::get<0> or boost::get<0>, you don't even need to convert to a tuple - it "just works" on std::pair, boost::tuple, std::tuple, or any other random-access Fusion sequence. Regards, Nate