Struct template is_component<T, typename boost::enable_if< is

Struct template is_component<T, typename boost::enable_if< is_filter< T > >::type>

boost::signals::is_component<T,typename boost::enable_if< is_filter< T > >::type> —

template<typename T> 
struct is_component<T, typename boost::enable_if< is_filter< T > >::type> {
};