id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
8603,BOOST_PARAMETER_CONSTRUCTOR with no required arugments,james.hirschorn@…,Daniel Wallin,"The following variation on the example from the boost::parameter tutorial, where the required parameter is changed to optional, fails to compile. myclass_impl is passed an empty agrument list.


{{{
#include <iostream>

#include <boost/parameter.hpp>


BOOST_PARAMETER_NAME(name)
BOOST_PARAMETER_NAME(index)

struct myclass_impl
{
    template <class ArgumentPack>
    myclass_impl(ArgumentPack const& args)
    {
        std::cout << ""name = "" << args[_name]
                  << ""; index = "" << args[_index]
                  << std::endl;
    }
};

struct myclass : myclass_impl
{
    BOOST_PARAMETER_CONSTRUCTOR(
        myclass, (myclass_impl), tag
            ,   (optional (name, *) (index, *)
                )
    ) // no semicolon
};

int main(int argc, char * argv[])
{
    myclass C(_name=""hello"", _index=0);
}

}}}

Compilation output:
{{{
In instantiation of 'myclass_impl::myclass_impl(const ArgumentPack&) [with ArgumentPack = boost::parameter::aux::empty_arg_list]':
...
}}}
",Bugs,closed,,parameter,Boost 1.53.0,Showstopper,invalid,BOOST_PARAMETER_CONSTRUCTOR,