Re: [Boost-users] question about multi_array use

On Aug 10, 8:30 am, Alle Meije Wink wrote:

...

On Sat, Aug 8, 2009 at 4:51 PM, Alle Meije Wink wrote: I like the look of boost::Fusion in terms of advanced generic C++ programming, but in terms of finding a concise description of my image template class / class / data type, this may be overshooting the aim a bit. Plus I will need to read up on template metaprogramming!

As someone who started using fusion recently, it really is remarkable. But it is a lot of work if you have never done metaprogramming before. The "C++ Template Metaprogramming" book is invaluable, even though it doesn't address fusion directly. One other (sub-optimal) method might be to fix a maximum number of dimensions that can be dealt with in the class and use it to initialize the multi_array: * When you construct an instance of the class with your "dimensions" loaded from the file, it could fill in the extents with the proper extents for the loaded data, and then put in a "1" for the other extents up to the maximum number of dimensions. * If you do this in the right order (i.e. put the single extents at the end rather than the beginning... or vice-versa depending on your storage ordering...) you might not have much of a performance hit since the strides might run through your real dimensions directly. * You can always address the multi_array indirectly by passing in a container of std::size_t indices, which you could pad with the appropriate number of "1"s depending on how many dimensions you are dealing with. * Or last, you could start recursively getting iterators from the multi_array to drop the dimension as many times as you have useless dimensions. * This all sounds like a pain, but it might not be that bad.