on Fri Feb 01 2008, Eric Niebler <eric-AT-boost-consulting.com> wrote:
Hansi Hansi wrote:
I have looked another time to the implementation of the histogram. If we want to implement it in the same class density, than it is needed to provide default parameter for density_cache_size or min/max. Is it possible to ensure that either density_cache_size or min/max is provided as parameter? Sorry for the question but I'm not so familiar with parameters...
Yes, it's possible. IIRC, a parameter pack is a valid MPL sequence, so you can us MPL algorithms to detect the presence or absence of any parameter.
boost::parameter::binding< argpack, tag::parametername, void >::type will tell you. If the result is void, the parameter wasn't supplied. -- Dave Abrahams Boost Consulting http://boost-consulting.com