Maurizio Vitale wrote:
Eric, I've found more about the root problem in my code. A pattern for a terminal was not matching and the thus the transform for unary_expr was applied.
In the code included, I define a class, K_aux, which inherits from meta_expression<typename proto::terminal<K<mpl::int_<N> >, Normally, objects of type K_aux match a pattern terminal<K<proto::_> >. I'm still fuzzy on why two layers of the type are skipped, but I'm fine with it.
Now, if K_aux defines a type named type (e.g. effectively becoming a nullary metafunction) the pattern doesn't match anymore.
Yep, I've known about this gotcha for a while and have been meaning to fix it before anybody noticed, but you beat me to it. :-P Proto uses the nested type named "type" to mean "the type of this expression", which was fine before proto::extends<> existed, but is dangerous and stupid once people start extending expression types. I'm sorry. Basically, I need to change all the nested types that Proto accesses to be proto-specific. So "type" becomes "proto_type", "tag_type" becomes "proto_tag", and even "arg0_type" becomes "proto_arg0", etc. This is a major breaking change, but it has to be done, and the sooner the better. Darn. -- Eric Niebler Boost Consulting www.boost-consulting.com The Astoria Seminar ==> http://www.astoriaseminar.com