On Apr 18, 8:34 pm, alfC wrote:

Hi,

 In Phoenix2 I used to have the following code to add expressions of type pow<N>(... expr...) which where useful for expressions involving Boost.Units. Is it possible to do something similar with Phoenix3. The usage if macros in the tutorial examples obscures how to add template parameters to the phoenix expression. In Phoenix2 it was straight forward, but I can figure out how to do this in Phoenix3.

ok, this is the farthest I could go with Phoenix3. It seems that the tag:: struct argument in phoenix::expr is a template template. The following is the latest attempt, which doesn't compile, giving the error: boost/phoenix/core/is_nullary.hpp:124:9: error: base type ‘const boost::proto::exprns_::basic_expr >, 0l> > >, 1l>&’ fails to be a struct or class type #include namespace boost{ namespace phoenix{ namespace tag{ template<long N> struct pow{}; } namespace expression { template struct pow : boost::phoenix::expr< tag::pow<N> , A0 > {}; } } namespace phoenix_impl{ template<long N> struct pow_impl{ template<class Sig> struct result; template struct result{ typedef double type; // just for testing }; template typename result::type operator()(Arg const& arg, Cont const& ctx) const { return boost::units::pow<N>(eval(arg, ctx)).value(); //value, just for testing } }; } namespace phoenix{ template typename expression::pow::type const pow(Arg const& arg){ return expression::pow::make(arg); } } }