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Subject: Re: [boost] Metaprogrammers, all of you!
From: Andrew Sutton (asutton.list_at_[hidden])
Date: 2010-10-13 10:15:45

> For the mere mortals among us, who are struggling to keep up with the
> metaprogramming astronauts, am I right in thinking that you are lamenting
> the emphasis on 'bells and whistles' to support SIMD iterators, while the
> more fundamental aspects of iterator segmentation are being ignored?

That's how I've read the discussion. The previous thread seems to have
trailed off into a space that more to do with particulars and little to do
with the fundamental abstraction.

On the topic of abstraction, I would say that Matt's solution seems to be
the right approach -- from an iterator perspective. He claims that
segmentation concepts is an orthogonal to the standard iterator concepts. I
don't especially like the implementation, requiring an explicit
specialization of segmented_iterator_traits. I see nothing preventing the
segmented iterator class from defining those associated types and operations
and allowing the traits class to use them by default.

The solution seems to fit the GP pattern quite well. Specialize generic
algorithms for orthogonal or refined concepts to get faster code for "free".

I don't really know enough about Fusion to comment on the design, but on the
surface it seems like an equivalent solution.

> And in your last remark are you saying you fear that metaprogramming and
> the Boost MPL are monsters!?

My feeling on metaprogramming (and hence the MPL) is that it's a necessary
evil for the style of generic programming going on here: necessary because
it's the duct tape that holds generic libraries together, evil because it
allows us to focus on really low-level details while doing some really
clever programming. In case this may have read differently, I think that
this style of generic programming is actually a good thing.


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