Re: [boost] [fusion] segmented fusion 2.0

Subject: Re: [boost] [fusion] segmented fusion 2.0
From: Eric Niebler (eric_at_[hidden])
Date: 2011-08-21 22:22:46

On 8/20/2011 7:36 PM, Joel de Guzman wrote:
> On 8/20/2011 5:41 AM, Eric Niebler wrote:
<snip>
>> Of course, single-stepping through a joint_view isn't necessarily the
>> most common use scenario. These things will also be passed to fusion
>> algorithms, which (if they are segment-aware) may in fact compile
>> /faster/ if joint_view is segmented (unconfirmed). :-/
>>
>> Regardless, it seems I need to improve the compile time of incrementing
>> and comparing generic segmented iterators.
> 
> That is interesting. If single-stepping through a joint_view isn't
> necessarily the most common use scenario, do you think invoke can
> be implemented another way? 

I think it could be done with variadic templates, but I'm not saying
invoke's implementation needs to change.

> AFAICT, invoke is a real world use-case.

No doubt!

> Perhaps we should be thinking more in terms of algorithm composition
> from primitives such as fold, but the very notion of 'iterators'
> suggest (and we c++ folks take it as norm), that we iterate through
> the elements in a step-wise manner (unless I misunderstood what you
> mean by "single-stepping").

Single-stepping though a joint_view is an important use case, and it
needs to be well-supported. No argument. Which is why I'd like to find
and fix the perf problem in segmented_iterator, or else leave
joint_view_iterator alone.

-- 
Eric Niebler
BoostPro Computing
http://www.boostpro.com