Re: [boost] mpl help needed - doing the impossible?

From: Manfred Doudar (manfred.doudar_at_[hidden])
Date: 2005-11-16 07:04:11

Martin Bonner wrote:

>>Manfred Doudar wrote:
>>
>>    
>>
>>>/* Now, how do I get T out when Rank == 1, ... compiler complains
>>>  about seeing a MyArray/blitz::Array of <T, Rank = 0>
>>>  (, which is not defined for blitz Arrays)
>>>*/
>>>template <typename T, int Rank>
>>>typename boost::mpl::if_
>>>                        < typename boost::mpl::equal_to
>>>                          < boost::mpl::int_<Rank>
>>>                          , boost::mpl::int_<1>
>>>                          >::type
>>>                        , T
>>>                        , blitz::Array<T,
>>>                                
>>>boost::mpl::int_<Rank>::prior::value> 
>>>
>>>
>>>      
>>>
>>                            ^
>>                            Oops typo, should be:
>>                                MyArray<T,
>>                                 
>>boost::mpl::int_<Rank>::prior::value> 
>>
>>... but nonetheless, the problem remains ...
>>
>>    
>>
>>>                        >::type
>>>MyArray<T, Rank> :: operator[] (const int& index) throw(); {
>>>  // Slicing
>>>      
>>>
>
>How about a helper traits class?
>
>template <typename T, int Rank>
>struct SliceType
>{
>  typedef typename MyArray<T, Rank-1> type;
>};
>
>template <typename T>
>struct SliceType<T,1>
>{
>   typedef T type;
>};
>
>template <typename T, int Rank>
>typename SliceType<T,Rank>::type
>   MyArray<T,Rank> :: operator[] (const int& index) throw();
>
>  
>

Doh! ... that looks like it might just work.

I'll give it a try

Thanks very much Martin.

Cheers,
-- 
Manfred Doudar
MetOcean Engineers
www.metoceanengineers.com