Re: [boost] [fusion] constructing all elements of the fusion vector with the same argument

From: Joel de Guzman (joel_at_[hidden])
Date: 2008-07-15 22:53:11

Stjepan Rajko wrote:

>> How about hacking on the /lazy_sequence/ idea? Thoughts?
>>
> 
> I *love it*.  Attached is something... similar ;-) (I used the
> triple.cpp example as a starting point, it was pretty straightforward)
> 
> What do you think?

I Love it! I think this should be an official part of Fusion.
There are some matters though that we should consider
very well:

1) The concept of an infinite-sequence.

    I'm not quite happy that all sequences has a finite size.
    Perhaps we can return something like fusion::infinite_size
    for size for such kind of sequences. We'll have to tweak the
    library though to cater to these kinds of sequences. IFAIR,
    these size checks are only done with algos dealing with 2
    sequences and one sequence need to have equal or more elements
    than the other. Better check on this one.

    If this is possible, then we should have a new infinite-sequence
    concept. I wonder where and how that will fit in the fusion
    concepts hierarchy.

2) If this is not possible, then the interface should at least
    be compatible with the at_c and at interfaces:

    make_lazy_sequence<MPL-N>(f);
    make_lazy_sequence_c<N>(f);

    and of course, its result_of counterparts.

Then, oh well... docs. Where should we put this? views, I guess.
A lazy_sequence is a kind of a view, I would say. I'll need docs
before something can be an official citizen. Hmmm.. I'll add a
"contributions" section for acknowledgment of these and future
contributions.

At any rate, amazing! THANK YOU!

Regards,
-- 
Joel de Guzman
http://www.boostpro.com
http://spirit.sf.net