Re: [Boost-users] [Phoenix] Ignore last post.

I realized some of the things I was doing in the sample code are pretty stupid. I'm still not sure why the compilation was failing on the phoenix code. I'll repost once I figure out what I'm doing. Sorry for the noise. On Tue, Nov 24, 2009 at 12:09 PM, James Knight wrote:

I'm having a problem using Boost.Phoenix. I'm currently building against Boost 1.41 using gcc 4.3.2.

I've simplified my use case quite a bit, so please forgive the obtuseness of the example. The following code fails to compile:

~~~~~~~~~~~~~~~~~~~~

#include #include #include #include

#include <vector>

#include <map> #include <algorithm>

namespace phx = boost::phoenix; using namespace phx::arg_names; using phx::at_c; using std::map;

using std::multimap; using std::vector;

int main() {

typedef map char_int_map_t; typedef multimap int_iter_map_t; typedef map char_iter_map_t;

int int_key = 5;

char_int_map_t int_map;

int_iter_map_t int_iter_map;

char_iter_map_t char_iter_map1, char_iter_map_t2;

int_iter_map_t::iterator start,stop;

std::pair

er = int_iter_map.equal_range(int_key);

std::set_intersection( char_iter_map1.begin(), char_iter_map1.end(), er.first,er.second, inserter(char_iter_map_t2,char_iter_map_t2.begin()), phx::at_c<0>(arg1) < phx::at_c<0>(*phx::at_c<1>(arg2)) // <- COMPILE FAILURE ); }

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here is the information I can offer,

1) When the key in char_int_map_t and char_iter_map_t is a char rather than a vector<char> this compiles without problems. 2) The gcc error shows that the arguments to the generated function object are being switched (I think, see below)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ... .../comparison.hpp:29:5: error: no match for ‘operator<’ in ‘result_of_less::x < result_of_less::y’ .../comparison.hpp: In instantiation of ‘const int result_of_less::index’: .../comparison.hpp:29: instantiated from ‘result_of_less’ .../mpl/eval_if.hpp:38: instantiated from ‘eval_if, is_actor, mpl_::bool_<false>, mpl_::bool_<false>, mpl_::bool_<false> >, re_curry, result_of_less&> >’ .../comparison.hpp:39: instantiated from ‘

boost::phoenix::less_eval::result< boost::phoenix::basic_environment<

std::pair< // This should be the second argument, no? const int,

std::_Rb_tree_iterator, int>> >, std::pair< const std::vector< char, std::allocator<char> >, std::_Rb_tree_iterator, int>> > >, boost::phoenix::composite< boost::phoenix::at_eval<0>, boost::fusion::vector< boost::phoenix::argument<0> > >, boost::phoenix::composite< boost::phoenix::at_eval<0>, boost::fusion::vector< boost::phoenix::composite< boost::phoenix::dereference_eval, boost::fusion::vector< boost::phoenix::composite< boost::phoenix::at_eval<1>, boost::fusion::vector< boost::phoenix::argument<1> > > > > > >

...

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

3) Finally, if I use the expression

phx::at_c<0>(arg1) < *phx::at_c<1>(arg2)

the code still fails to compile (obviously), but does seem to get the arguments in the correct order.

Any ideas?

Thanks Nate