Re: [boost] Interest in super string class?

From: Joel de Guzman (joel_at_[hidden])
Date: 2006-07-05 18:17:42

Jody Hagins wrote:
> On Wed, 05 Jul 2006 22:35:47 +0800
> Joel de Guzman <joel_at_[hidden]> wrote:
> 
>> The result will be a view. Then, if it's done correctly, ideally,
>> the view transformations can collapse the view. IOTW, this:
>>
>>      to_lower_view<to_upper_view<range> >
>>
>> will be optimized to:
>>
>>      to_lower_view<range>
>>
>> and:
>>
>>      to_upper_view<to_lower_view<range> >
>>
>> will be optimized to:
>>
>>      to_upper_view<range>
>>
>> Hence, the entire to_upper(to_lower(to_upper(rng))) will be
>> collapsed to:
>>
>>      to_upper(rng)
> 
> 
> 
> That's a whole bunch of assumptions, both on the compiler and the
> developer, not to mention the semantics of each "view."  I've used views
> on numerous occasions, and while they give the appearance of "no cost"
> they do, quite often, incur significant overhead.  Both for the view
> abstraction itself, and the shenanigans behind the scene when the real
> underlying data changes.
> 
> Hey, they are great for some things, but I do not see how they can be
> the endall that eliminates mutable interfaces...

Maybe. But unless you provide some benchmarks and numbers, what
you are hinting at has no weight, as far as I'm concerned.

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