Re: [boost] [function] Merits of drop-in replacement

From: Michael Marcin (mmarcin_at_[hidden])
Date: 2007-09-18 14:20:28

Tobias Schwinger wrote:
> Doug Gregor wrote:
>> On Sep 14, 2007, at 4:05 PM, Michael Marcin wrote:
>>
>>> I ran across http://www.codeproject.com/cpp/fastdelegate2.asp the  
>>> other
>>> day.  I searched the archives and didn't find any discussion about  
>>> it on
>>> the list.
>>>
>>> It makes some good arguments and seems to be done pretty well,  
>>> although
>>> it may have succumb to a bit of feature creep.
>>>
>>> Should those benchmarks be reran against the trunk version of
>>> Boost.Function?
>> Yes, those tests should certainly be rerun now that Boost.Function  
>> does the small-object optimization. Copy performance for such small  
>> objects is much, much improved.
> 
> I once hacked a quick benchmark to compare dispatch times of 
> Bind&Function (1.34 versions) vs. FastDelegate.
> 
> With an inlineable replacement for 'boost::mem_fn' (accepting the member 
> function pointer as a non-type template argument)
> 
>      http://tinyurl.com/37tkap
> 
> FastDelegate turned out to be (not quite) twice as fast as Function&Bind 
> with MSVC, which isn't that much IMO held against the lost flexibility, 
> such as not being able to use arbitrary function objects and only 
> binding 'this'.
> 
> However, things looked quite a bit worse with GCC (version 4 IIRC, don't 
> remember the exact numbers), a good chunk of it because of not-optimized 
> compile-time const member pointers.
> 
> So FastDelegate is still be several times faster when it comes to member 
> function pointers that are runtime values...
> 
> 
There are several fast delegates floating around. I saw discussion in 
the archives about:

http://www.codeproject.com/cpp/fastdelegate.asp

but not

http://www.codeproject.com/cpp/fastdelegate2.asp

which is completely different AFAIK.

Which did you compare against before?

Thanks,

Michael Marcin