----Original Message---- From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of Joel de Guzman Sent: 29 September 2006 00:25 To: boost@lists.boost.org Subject: Re: [boost] [fusion] Support for classic boost::tuple
David Abrahams wrote:
Joel de Guzman <joel@boost-consulting.com> writes:
Joel de Guzman <joel@boost-consulting.com> 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,
David Abrahams wrote: 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,
I think the problem is, should pair<int*,int*> a_pair_of_pointers; be treated the same as int* two_pointers[2]; or the same as int an_array_of_ints[ pair.second-pair.first ] The first is the obvious answer if you treat the pair as a special form of tuple. The second is the obvious answer is you consider the pair as two iterators over a sequence (like the Boost Range library). -- Martin Bonner Martin.Bonner@Pitechnology.com Pi Technology, Milton Hall, Ely Road, Milton, Cambridge, CB4 6WZ, ENGLAND Tel: +44 (0)1223 203894