From: Eric Niebler (eric_at_[hidden])
Date: 2007-06-16 02:02:22
Eric Niebler wrote:
> Maurizio Vitale wrote:
>> 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.
This bug should now be fixed. This involved a massive number of breaking
renames, so I think this should probably break just about everybody. Sorry.
The following Proto expression nested types/members have been renamed:
type -> proto_base_expr
tag_type -> proto_tag
args -> proto_args
arity -> proto_arity
domain -> proto_domain
arg0_type -> proto_arg0
arg1_type -> proto_arg1
boost_proto_expr_type_ -> proto_derived_expr
cast() -> proto_base()
In addition, there used to be a "proto::trans" namespace alias for
proto::transform, and I've remove that. Bad idea. Gotta say "transform"
now, or else create your own alias.
-- Eric Niebler Boost Consulting www.boost-consulting.com The Astoria Seminar ==> http://www.astoriaseminar.com
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