Re: [Boost-users] [spirit][karma+phoenix] Show result of member function

Subject: Re: [Boost-users] [spirit][karma+phoenix] Show result of member function
From: Hartmut Kaiser (hartmut.kaiser_at_[hidden])
Date: 2010-04-04 13:58:47

I'm traveling, so won't be able to get back on this before Tuesday.

Regards Hartmut

---------------
Meet me at BoostCon
www.boostcon.com

> -----Original Message-----
> From: boost-users-bounces_at_[hidden] [mailto:boost-users-
> bounces_at_[hidden]] On Behalf Of Ravi
> Sent: Saturday, April 03, 2010 8:22 PM
> To: boost-users_at_[hidden]
> Subject: [Boost-users] [spirit][karma+phoenix] Show result of member
> function
> 
> Hi,
>   How can karma be used to show the result of applying a member
> function to
> objects in a container? Consider the following code (which does not
> compile)
> to show the real and the imaginary parts of complex numbers stored in a
> vector:
> 
> --8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----8<-
> -
> #include <boost/spirit/include/karma.hpp>
> #include <boost/spirit/include/phoenix_bind.hpp>
> #include <boost/spirit/include/phoenix_core.hpp>
> #include <boost/spirit/include/phoenix_operator.hpp>
> 
> #include <complex>
> #include <iostream>
> #include <vector>
> 
> namespace test {
> 
> template <typename Container>
> void show_container( const Container &ctr )
> {
>   typedef typename Container::value_type complex_t;
>   typedef typename complex_t::value_type real_t;
>   const real_t& ( complex_t::*real_func )() const = &complex_t::real;
>   const real_t& ( complex_t::*imag_func )() const = &complex_t::imag;
> 
>   namespace karma = boost::spirit::karma;
>   namespace phoenix = boost::phoenix;
> 
>   std::cout <<
>     karma::format(
>       (
>         karma::double_[
>           // What goes here to extract the real part?
>           karma::_1 = phoenix::bind( real_func, karma::_val )
>           ]
>         << ','
>         << karma::double_[
>           karma::_1 = phoenix::bind( imag_func, karma::_val )
>           ]
>         ) % karma::eol,
>       ctr );
> }
> 
> } // namespace test
> 
> int main( int, char *[] )
> {
>   std::vector< std::complex<double> > vec( 5 );
>   test::show_container( vec );
>   return 0;
> }
> --8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----8<-
> -
> 
> The issue is that "karma::_1 = phoenix::bind( real_func, karma::_val )"
> seems
> unacceptable to the compiler (gcc 4.4.3, boost 1.42, Linux x86_64). The
> example above is a simplified version of much more complex code.
> 
> Regards,
> Ravi
> 
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