Re: [Boost-users] mpl::transform<...> --- compile error: is not derived from type

Subject: Re: [Boost-users] mpl::transform<...> --- compile error: is not derived from type
From: e r (erwann.rogard_at_[hidden])
Date: 2008-09-07 17:37:23

e r wrote:
> e r wrote:
>> hi,
>>
>> here's the problem i have:
>>     struct my{
>>       template<typename UInt>
>>       struct apply{
>>            typedef mpl::int_<UInt::value> type;
>>       };
>>    };
>>
>>     template<int First,int Last>
>>     struct id_range{
>>         typedef mpl::transform<
>>             mpl::range_c<int,First,Last>
>>             , my
>>             , mpl::back_inserter< mpl::vector<> >
>>         >::type type;
>>
>> /home/er/cpp/boost/random/mcmc/id_range.hpp|32|error: type
>> ‘boost::mpl::transform<boost::mpl::range_c<int, First, Last>,
>> boost::random::mcmc::<unnamed>::my,
>> boost::mpl::back_inserter<boost::mpl::vector<mpl_::na, mpl_::na,
>> mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na,
>> mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na,
>> mpl_::na, mpl_::na, mpl_::na, mpl_::na> >, mpl_::na>’ is not derived
>> from type ‘boost::random::mcmc::id_range<First, Last>’|
>>
>> however, for example, this --instead-- compiles fine:
>>
>>     struct id_range{
>>         typedef mpl::transform<
>>             mpl::range_c<int,1,3>
>>             , my
>>             , mpl::back_inserter< mpl::vector<> >
>>         >::type type;
>>  };
>> any suggestion appreciated. thanks!
> 
> 
> and also, although the second version compiles, i have
> 
>     BOOST_MPL_ASSERT( (
>             is_same<
>                 id_range::type,
>                 mpl::vector< mpl::int_<1>, mpl::int_<2>, mpl::int_<3> >
>             >
>     ) );
> 
> causes,
> 
> error: no matching function for call to
> ‘assertion_failed(mpl_::failed************
> boost::is_same<boost::mpl::v_item<mpl_::int_<2>,
> boost::mpl::v_item<mpl_::int_<1>, boost::mpl::vector<mpl_::na, mpl_::na,
> mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na,
> mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na,
> mpl_::na, mpl_::na, mpl_::na, mpl_::na>, 0>, 0>,
> boost::mpl::vector<mpl_::int_<1>, mpl_::int_<2>, mpl_::int_<3>,
> mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na,
> mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na,
> mpl_::na, mpl_::na, mpl_::na> >::************)’|

In the first post: there's a typename missing, which solves the problem.