[Boost-users] [Accumulators] How to define the initial value ?

Hi everyone, As the code of weighted_sum_impl constructor is [ in header ] template<typename Args> weighted_sum_impl(Args const &args) : weighted_sum_( args[parameter::keyword<Tag>::get() | Sample()] * numeric::one<Weight>::value ) { } and the template parameter Tag is defined as tag::sample namespace tag { struct weighted_sum : depends_on<> { typedef accumulators::impl::weighted_sum_impl impl; }; } How can I define this tagged argument when initializing the accumulator_set ? ( Indeed, weighted_sum_impl constructor is called at this point ) Thanks in advance for your help. Adrien