Re: [boost] If boost::fusion is the hammer, then what's the nail?

From: Gennadiy Rozental (gennadiy.rozental_at_[hidden])
Date: 2006-12-15 11:56:00

"David Abrahams" <dave_at_[hidden]> wrote in message 
news:87psal1e9x.fsf_at_pereiro.luannocracy.com...
> "Gennadiy Rozental" <gennadiy.rozental_at_[hidden]> writes:
>
>> "David Abrahams" <dave_at_[hidden]> wrote in message
>> news:87lkl93hlx.fsf_at_pereiro.luannocracy.com...
>>> "Gennadiy Rozental" <gennadiy.rozental_at_[hidden]> writes:
>>>
>>>> This is not clear cut. I do not see in theory why any boost::variant
>>>> based
>>>> algorithm couldn't be optimized to almost the same code (module type
>>>> switching). On the other hand excessive usage of tuples will cause
>>>> appropriate code bloat, eventually leading to code slow down.
>>>
>>> Not clear cut at all.  When operating on a sequence where all the
>>> types are different, the version with variant will be both slower and
>>> larger.
>>
>> I love these performance "estimations"
>>
>> Do you have any numbers to sustain this?
>
> No, sorry.  It's simply obvious.
>
> Feel free to prove me wrong if it isn't obvious to you.

Nah. I don't really care. Just that after many years of optimizing 
performance critical code I gave up doing any "estimations". I was proven 
wrong too many times, so that  even test program is not real prove. There 
are way too many factors that affect performance of real-life applications. 
Sometimes the same code compiled with different compilers of in different 
hardware will exhibit completely different performance pattern. We could 
talk about trends. And in this case I believe trends could be different 
depending on circumstances.

Gennadiy