[Boost-users] [boost parameter] misusing deduced

22 Feb 2009

      er wrote:
...
Hello,
Comments are in the code. Any help appreciated.
*.hpp
template<typename RealType,typename Id>
    class mu
      : public accumulator_base
    {
        typedef mu<RealType,Id> self_type;
        typedef parameter::deduced<self_type>       par0_type;
        typedef parameter::parameters<par0_type>    params;
        public:
        typedef RealType    result_type;
        mu(result_type value):value_(value){}
template<typename Args>
        mu(const Args& args):value_((result_type)(0)){
    // compile bottleneck (caused by the assigment, not the rhs)
            const self_type& input = params()(args);
            value_ = input.value_;
        }
        private:
        result_type value_;
    };
*cpp:
typedef mpl::int_<0> id0_t;
    typedef accumulators::tag::mu<id0_t> mu0_t;
    typedef boost::mpl::vector<
        mu0_t
    >                                           explicit_entities;
typedef double value_type;
    typedef accumulators::accumulator_set<
        value_type,
        explicit_entities
    >                                           acc_type;
typedef mpl::apply<mu0_t::impl,value_type>::type input0_type;
input0_type input0(0.5);
    // acc_type acc; // compiles fast
    acc_type acc((input0)); // compiles forever
I've realized I wasn't using deduced properly. Something like this?

	typedef parameter::parameters<
		parameter::required<
             parameter::deduced<tag_type>,
             is_same<mpl::_1,self_type>
         >
	> params;

Should allow and ArgPack of the form ((tag = x)) or ((x)), provided x is 
of type self_type, right?