\brief Metafunctions to work with tagged types.
This metafunctions aims to make easier the manage of tagged types. They are all mpl
-compatible metafunctions and can be used with lambda expresions.
+compatible metafunctions and can be used with lambda expressions.
The metafunction value_type_of and tag_of get the data in a tagged type in a secure
and consistent way.
default_tagged and overwrite_tagged allows to work with the tag of a tagged type,