Hi Fabien, I have never used or even heard of cached_location. So, I don't feel comfortable to answer design decisions. Sorry, Christian On Sun, Dec 12, 2010 at 2:37 PM, fabien <fabien.castan@free.fr> wrote:

Hi, I like the idea of cached_location, but I have some questions about it.

//// a simple usage example: // get a temporary locator from the view const SLocator loc_ref = srcView.xy_at(0,0); // from this locator we can extract a cached_location typename SLocator::cached_location_t LT( loc_ref.cache_location(-1,-1) );

DPixel func( const SLocator& src ) {        // now instead of doing this:        return src(-1, -1);

       // we can directly retrieve the pixel        // from the locator using this cached location        return src[LT]; }

I have 2 questions: 1) Why can't we directly get a cached_location from a view (without using a locator) ? We have all informations in the view to build it, isn't it ? typename SLocator::cached_location_t LT( srcView.cache_location(-1,-1) );

2) Is there a good reason to not allows to get a locator from another locator using cached_location ?

DLocator func( const SLocator& src ) {        // we can do this        return src.xy_at(-1, -1); // return a new locator

       // we can't do the same thing with cached_location        return src.xy_at(LT); //< it can be interesting to do this ! }

Same remark to get an x_iterator from a locator: src.x_at(-1, -1); //< we can do this src.x_at(LT); //< we can't do this

Best regards, Fabien Castan _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost