[Boost-users] [boost parameter] misusing deduced

Subject: [Boost-users] [boost parameter] misusing deduced
From: er (erwann.rogard_at_[hidden])
Date: 2009-02-22 19:31:04

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?