On Sat, Apr 19, 2014 at 09:03:30AM -0500, Dick Hollenbeck wrote: > For me it seems context specific, and I would not feel comfortable saying one > strategy > fits all contexts. A dynamic cast has to be about 100 times slower than a C > style cast, > and therefore you would not use that unless you can afford the hit.
Well, a static cast should be by definition zero cost (except in newer C++ where constructor and temporaries are allowed, or some minor vtbl pointer tweaking), while a dynamic cast is done with an utility function (in libsupc++, for gcc). So the cost maybe doesn't reach 100:1 but at least 10:1 would be plausible. If there is virtual inheritance static_cast should be the best thing for a downcast *if* there is no virtual inheritance around (AFAIK kicad doesn't have it) and the type is certain. dynamic_cast is strictly needed for v.i. or when the type is not known. So I'd recommend static_cast inside an if(Type() == x) block and a dynamic otherwise. Of course in 'proper' C++ style the whole Type() machinery wouldn't exist anyway and everything should work with vtbls... maybe in 10 years, on kicad :D -- Lorenzo Marcantonio Logos Srl _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp
