Re: [Boost-users] [phoenix] lazy function to reference or const reference

Subject: Re: [Boost-users] [phoenix] lazy function to reference or const reference
From: alfC (alfredo.correa_at_[hidden])
Date: 2011-04-04 13:47:33

On Apr 4, 2:53 am, Thomas Heller <thom.hel..._at_[hidden]> wrote:
> I messed up in the type calculation ;)
> Thanks for reporting, the issue is now fixed on trunk.
>

great, thanks, now it works.

What I wanted to achieve was a function class that is at the same time
a lazy function,
  A a;
  a(5.); //calls the usual operator()
  a(arg1 + 1.); // build a phoenix expression

maybe implemented like below. However I can't, the compilation error
was
usr/include/boost/type_traits/is_abstract.hpp:72:4: error: incomplete
type ‘A’ not allowed.

Is there an elegant way to achieve this? -- Thanks -- Alfredo

#include<boost/phoenix/core.hpp>
#include<boost/phoenix/function.hpp>

struct A : boost::phoenix::function<A&> {
    A() : boost::phoenix::function<A&>(*this){}
    template <typename Arg>
    struct result{
        typedef double type;
    };
    using boost::phoenix::function<A&>::operator();
    template<typename Arg>
    double operator()(Arg arg1) const{
        return 5.;
    }
};