[Boost-users] [fusion] iterating over a sequence with non-const references

Subject: [Boost-users] [fusion] iterating over a sequence with non-const references
From: paul Fultz (pfultz2_at_[hidden])
Date: 2012-03-31 14:08:57

Hi,
I would like to iterate over a sequence and preserve the 

reference/const/non-const of the elements. That is say I have
a sequence like this:

    tuple<int&, int> seq;

I would like to this to be true:

    typeof(deref(begin(seq))) == int&
    typeof(deref(next(begin(seq)))) == int&&

It seems fusion sequences always return a const reference to
the element. Is there a workaround to get it to work like this?
Or is this just not possible with Boost.Fusion?
Furthermore, I would like to use the transformation algorithms
(especially push_back, and push_front) and still preserve the
reference type. Is that possible, through some workarounds?
Finally, would it still be fairly efficient when dealing with 

references, to copy the tuple and make a new tuple when doing
algorithms such as push_back or push_front? Or is the lazy 

evaluation much more efficient than that?

Thanks,
Paul Fultz II