Re: [Boost-users] loop vs. for_each & boost::bind

From: steve ahlgren (steveahlgren_at_[hidden])
Date: 2005-04-20 16:24:46

Hello :

Try using boost::ref to avoid creating a copy of the arguments (see
http://www.boost.org/doc/html/ref.html ) :

std::for_each(	rr.begin(),
                                rr.end(),
                                boost::bind( boost::mem_fn( &Region::render ), 
                                                        _1, 
                                                        boost::ref( ltt ), 
                                                        foo, 
                                                        boost::ref( si ) 
                                                        )
                                );

Good luck!

On 4/20/05, Mathieu De Zutter <mathieu_at_[hidden]> wrote:
> Hi,
> 
> I have some code that runs fine:
> 
> for (Partition::iterator pi = renderRegions.begin(); pi !=
>         renderRegions.end(); ++pi);
>     (*pi)->render(&ltt, foo, si);
> 
> I try to replace it by for_each & boost::bind,
> 
> std::for_each(renderRegions.begin(), renderRegions.end(),
>     boost::bind(&Region::render, _1, &ltt, foo, si));
> 
> but si doesn't get modified, while it should be passed as reference.
> 
> Some more relevant code:
> 
> class Region
> {
>     ...
>     void render(const LightTransportType* ltt, WorkAppraiser& wa,
>         image::SampleImage& result);
>     ...
> };
> 
> typedef std::vector< Region* > Partition;
> Partition renderRegions;
> 
> Is this normal behaviour?
> 
> --
> With kind regards,
> Mathieu
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