Re: [Boost-users] [Tuple] augment_tuple, patch, or whatever... maybe MPL?

Subject: Re: [Boost-users] [Tuple] augment_tuple, patch, or whatever... maybe MPL?
From: Hossein Haeri (powerprogman_at_[hidden])
Date: 2010-11-23 08:51:28

Yup. Thanks! :)

--- On Tue, 23/11/10, Robert Jones <robertgbjones_at_[hidden]> wrote:

From: Robert Jones <robertgbjones_at_[hidden]>
Subject: Re: [Boost-users] [Tuple] augment_tuple, patch, or whatever... maybe MPL?
To: boost-users_at_[hidden]
Date: Tuesday, 23 November, 2010, 13:21

On Tue, Nov 23, 2010 at 12:05 PM, Hossein Haeri <powerprogman_at_[hidden]> wrote:

Dear all,

Is there any function in Boost.Tuple which works like this for n-tuples for any given n?

template<typename T1, typename T2, typename T3>

tuples::tuple<T1, T2, T3> augment_tuple(tuples::tuple<T1, T2> tup, T3 t3)

{

  return tuples::make_tuple(tup.get<0>(), tup.get<1>(), t3);

}

(Obviously, here n == 2.) The purpose of this augment_tuple (or, patch, or whatever) is to take an n-tuple and a new element and patch the new element to the end of the n-tuple in order to get a (n + 1)-tuple. Repetitive code which can produce enough overloads for a large enough n is of course trivial. I'm wondering whether MPL has a utility which can automated this though?

I think this is what you need. Since Boost.Tuple can be a conforming ForwardSequence (with the appropriate header),
this does exactly what you want.

http://www.boost.org/doc/libs/1_43_0/libs/fusion/doc/html/fusion/algorithm/transformation/functions/push_back.html

- Rob.

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