Re: [boost] [Function][Bind] Re: "Smallbufferoptimization"forboost::function?

From: Peter Dimov (pdimov_at_[hidden])
Date: 2006-01-15 06:15:06

Alex Besogonov wrote:
> Peter Dimov wrote:
>> Anyway, I committed a storage optimization to the CVS. <crosses
>> fingers>
> Whoa! That's fast:
> ================================
> C:\temp\delegates>test.exe
> Time elapsed for FastDelegate: 0.560000 (sec)
> Time elapsed for simple bind: 0.411000 (sec)
> Time elapsed for bind+function: 1.983000 (sec)
> Time elapsed for pure function invocation: 0.781000 (sec)
> ================================
> bind+function<> is now just 4 times slower than the best possible
> case.
>
> BTW, why not add FastDelegate (it's in public domain) to
> bind+function<> as a special case for optimization?

Most of the time is probably due to function<>'s dynamic dispatch mechanism; 
I'm not sure how FastDelegate can help.

You could also try a test using ct_mem_fn< void (X::*)(), &X::f > where 
ct_mem_fn is:

template< class Pm, Pm pm > struct ct_mem_fn
{
    typedef void result_type;

    template<class A1> result_type operator()( A1 & a1 ) const
    {
        boost::mem_fn( pm )( a1 );
    }

    template<class A1, class A2> result_type operator()( A1 & a1, A2 & a2 ) 
const
    {
        boost::mem_fn( pm )( a1, a2 );
    }
};