Hicham Mouline wrote:

-----Original Message----- From: "Hicham Mouline" [hicham@mouline.org] Date: 23/02/2010 02:53 PM To: boost-users@lists.boost.org Subject: Re: fusion result_of::at<Seq, N>::type doesn't return the type I expect

std::cout<< boost::is_same< t0, double >::value <<std::endl; I am certain I am missing something obvious,

rds,

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I needed to compare t0 with double& and not double,

rds,

Hi, It's not that clear from your example whether you expect a ref or a value. The doc says this : Returns a reference to the N-th element from the beginning of the sequence seq. Since I've recently discovered this wonderful facility that fusion adapt is, I wanted to make sure it wasn't returning a value for the custom classes (fx_) that I have adapted : typedef boost::fusion::result_of::at_key<fx_,key_>::type result_; typedef double& expected_; typedef boost::is_same<result_,expected_> same_; BOOST_STATIC_ASSERT(same_::value); Compiles fine. Also, typedef boost::fusion::result_of::at_key<const fx_,key_>::type result_; typedef const double& expected_;