Re: [boost] [fusion] Support for classic boost::tuple

From: Joel de Guzman (joel_at_[hidden])
Date: 2006-09-28 19:25:25

David Abrahams wrote:
> Joel de Guzman <joel_at_[hidden]> writes:
> 
>> David Abrahams wrote:
>>> Joel de Guzman <joel_at_[hidden]> writes:
>>>
>>>> Hi,
>>>>
>>>> Ok, as promised. Support for classic boost::tuple has been added.
>>>> Now yer ole boost tuples are full fusion citizens. Now boost::tuple
>>>> can do for_each, transform, fold, find, assign/convert to other
>>>> fusion sequences, etc.
>>>>
>>>> Now there are 3 adapted sequences:
>>>> 1) std::pair
>>> This one is going to cause me issues.  I'm writing a unified library
>>> to operate on static and dynamic sequences.  Here's the
>>> issue:  is 
>>>
>>>    pair<int*,int*>
>>>
>>> a dynamic sequence that goes from the first pointer to the 2nd (as in
>>> Boost.Range), or a static sequence with 2 elements (a la Fusion)?
>> Both? I think, in as much as boost::array<int> is a dynamic
>> sequence that STL algorithms can operate on, and at the same
>> time, is also a static sequence fusion algorithms can handle,
>> the same should be true for mono-sequences like pair<int*,int*>.
> 
> [what's a mono-sequence?]

The opposite of hetero-sequence :P

> It's not the same thing at all.  In the case of array<int>, the
> sequence has the same elements in either case; we're just talking
> about two ways of accessing the same sequence.  In the case of
> std::pair there are two completely distinct interpretations, either of
> which could be valid.  In my case I think there are only two possible
> choices:
> 
>   1. say that std::pair needs to be wrapped or otherwise
>      transformed before I know how to treat it.
> 
>   2. pick one of the two interpretations.

I'm sorry. I think I'm lost. With:

     pair<int*,int*>

or

     tuple<int*,int*,int*,int*>

or

     array<int*>

I see the same elements. What am I missing?

Cheers,
-- 
Joel de Guzman
http://www.boost-consulting.com
http://spirit.sf.net