Re: [Boost-users] question about multi_array use

Subject: Re: [Boost-users] question about multi_array use
From: OvermindDL1 (overminddl1_at_[hidden])
Date: 2009-08-08 20:26:46

On Sat, Aug 8, 2009 at 4:51 PM, Alle Meije Wink<a.m.wink_at_[hidden]> wrote:
> Dear Overmind and Anton, thanks for your answers.
>
> Let's see if I understand!
>
> Yes, multi_array<int, 2> and multi_array<int,3> are different types
> (classes?). But I wouldn't mind using a template class to wrap it if that
> meant I could code it once, instead of 8 times for 8 different possible
> dimensionalities.
>
> Would it be able to define a template class in the way I described?
>
> Overmind, I guess compared to what I had in mind (define the data container
> of the image [template?] class as a multi_array with a dimensionality given
> as a size_t parameter), the CRTP struct you are talking about specifies all
> of the possible types. Is that correct?
>
> If I understand it correctly then this does what I want, but does that mean
> that in the worst-case scenario, I have to write out the functionality for
> all different dimensionalities? If the parameterised template class idea is
> possible, that would save some typing!
>
> Best wishes,
> Alle Meije
>>
>> From: OvermindDL1 <overminddl1_at_[hidden]>
>> To: boost-users_at_[hidden]
>> Subject: Re: [Boost-users] question about multi_array use
>> Message-ID:
>>        <3f49a9f40908071709rbd1ad80k4c5170093588f4d_at_[hidden]>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> On Fri, Aug 7, 2009 at 2:04 PM, Anton Daneyko<self_at_[hidden]> wrote:
>>
>>>
>>> Hello,
>>>
>>> I might be wrong, but it seems the answer is "no you can't do that",
>>> because
>>> the dimensionality is a template parameter multi_array<int, 2> and
>>> multi_array<int, 3> are different types. However I would like to hear
>>> some
>>> else' opinion as well.
>>>
>>> Regards,
>>> Anton Daneyko.
>>>
>>> On Fri, Aug 7, 2009 at 3:48 PM, Alle Meije Wink <a.m.wink_at_[hidden]>
>>> wrote:
>>>
>>>>
>>>> Hello,
>>>>
>>>> I would like to use the multi_array container to handle imaging data.
>>>> The
>>>> image data can be anything up to 8-dimensional (usually up to 4) and
>>>> dimension information is found in records that accompany the binary
>>>> data.
>>>>
>>>> Would it be possible to create an image class that takes the
>>>> dimensionality and extents list as parameters, so that images of all
>>>> dimensionalities can be treated as one class?
>>>>
>>>> For example, could the dimensionality be passed as a size_t argument?
>>>>
>>>> What I understand from the multi_array paper is that the extents list
>>>> would only be required whan the array is initialised.
>>>>
>>
>> You could always just wrap up each of the possible dimensions in a
>> struct that can handle the (de)serialization and everything too,
>> perhaps use crtp to put identical functionality in a non-virtual base
>> class.

I could see using fusion (mostly the "apply" construct) would make it
generic to any number of dimensions.  Boost.Fusion is amazing for such
work, think MPL, but it works at runtime too.