Re: [boost] Re: [MPL] Making Tuples

From: David Abrahams (dave_at_[hidden])
Date: 2002-12-17 08:09:16

Aleksey Gurtovoy <agurtovoy_at_[hidden]> writes:

> David A. Greene wrote:
>> Well, that's not creating a boost::tuple.  :)  I could certainly use
>> mpl::fold or some similar algorithm to create boost::tuple<int,
>> boost::tuple<...> > > > but I'm not sure that "really" a boost::tuple
>> either.  cons<int, cons<...> > > > might be closer.
>
> Yep, the later will give you all the functionality of
> 'boost::tuple<int,...>' except the constructors and assignment from
> 'std::pair'. A generator for it is as simple as this:
>
>     template< typename Types > struct tuple_gen
>         : fold_backward<
>               Types
>             , boost::tuples::null_type
>             , boost::tuples::cons<_2,_1>

Wow, is cons a metafunction?

It doesn't appear to be.  I know we discussed making non-metafunctions
usable as MPL lambda-expressions, but I didn't think you would opt for
the transparent approach, with automatic detection of nested ::type.

I thought you were going to require some explicit wrapper
template... Not that I mind this approach.

>

-- 
                       David Abrahams
   dave_at_[hidden] * http://www.boost-consulting.com
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