Re: [Boost-users] challange to MPL gurus

On 12/12/11 23:30, Larry Evans wrote:

On 12/12/11 22:49, Robert Ramey wrote: [snip]

...

I moved it back in - and voila - worked as expected. Here is my solution:

template<typename I> struct ForwardIterator { template struct is_end {};

template<typename I2> struct is_end { typedef typename deref<I2>::type t1; typedef typename next<I2>::type t2; BOOST_CONCEPT_ASSERT(( ForwardIterator<t2> )); };

typedef typename is_end< I, typename boost::is_same< boost::mpl::l_iterboost::mpl::l_end, I > > type; typedef typename boost::mpl::print< I >::type t1;

BOOST_MPL_ASSERT(( is_convertible< typename I::category, forward_iterator_tag > )); };

[snip] I couldn't get this code to compile with gcc-4.7-20111008. Before any revision, got:

ramey_iter_concept_check.cpp:22:14: error: declaration of 'class I' ramey_iter_concept_check.cpp:20:10: error: shadows template parm 'class I' ramey_iter_concept_check.cpp:32:22: error: expected nested-name-specifier ramey_iter_concept_check.cpp:38:7: error: invalid declarator before 'type'

After eliminating the showing I, as shown in the attached, I got:

/home/evansl/download/gcc/4.7-20111008/install/bin/g++ -c -Wall -Wstrict-overflow -ftemplate-depth-300 -O0 -g3 -fno-inline -std=gnu++0x -I/home/evansl/prog_dev/boost-svn/ro/trunk/sandbox/ro/numeric_bindings -I/home/evansl/prog_dev/boost-svn/ro/trunk/sandbox/rw/non_variadic_templates -I/home/evansl/prog_dev/boost-svn/ro/trunk -DTEMPLATE_DEPTH=300 ramey_iter_concept_check.cpp -MMD -o build/gcc4_7n/boost-svn/ro/trunk/sandbox/rw/variadic_templates/libs/mpl/example/ramey_iter_concept_check.o

ramey_iter_concept_check.cpp:31:22: error: expected nested-name-specifier ramey_iter_concept_check.cpp:37:7: error: invalid declarator before 'type' make: *** [build/gcc4_7n/boost-svn/ro/trunk/sandbox/rw/variadic_templates/libs/mpl/example/ramey_iter_concept_check.o] Error 1

I guess you're using MS or an earlier gcc.

-regards, Larry Using the if_recur.hpp:

http://svn.boost.org/svn/boost/sandbox/variadic_templates/boost/mpl/if_recur... mentioned in one of my previous replies, the attached compiles; however, I'm not sure it does what you want. The in source comments reflect my questions. -regards, Larry