A bug. It's fixed now on the trunk and release branches. Thanks.

Thank you, Eric. That works, but now proto::lazy isn't working with proto::fold. Below is a program you posted to boost.devel on 3/29/2008, updated with s/bind/lazy/ and s/_arg/_child/. It's giving me the following syntax error. Any idea what's wrong? Thanks, Dave Jenkins error C2664: 'Accumulator::Accumulator(const Accumulator &)' : cannot convert parameter 1 from 'Accumulator' to 'const Accumulator &' c:\boost\boost\proto\transform\call.hpp 156 #include <iostream> #include #include #include #include #include #include #include namespace mpl = boost::mpl; namespace proto = boost::proto; template<typename IsValid = mpl::true_, typename Value = void> struct Accumulator : IsValid { template<typename Value2> struct validate : mpl::and_< IsValid , mpl::or_< boost::is_void<Value> , boost::is_same > > {}; template<typename Sig> struct result; template struct result { typedef Accumulator type; }; template<typename Value2> typename result::type operator ()(Value2 const &) const { return typename result::type(); } }; struct SameTerminals : proto::or_< proto::when< proto::terminalproto::_ // treat the current state as a callable // object and pass it the value of the terminal. , proto::lazyproto::_state(proto::_child) > , proto::otherwise< proto::fold > > {}; int main() { int dummy = 0; proto::terminal<int>::type i = {0}, j = {1}, k = {2}; proto::terminal<short>::type s = {42}; BOOST_ASSERT( SameTerminals()(i+j*k, Accumulator<>(), dummy) ); BOOST_ASSERT(!SameTerminals()(i+s*k, Accumulator<>(), dummy) ); }

With this change, it works for me.

Works for me too. Thanks.