[request] Use delegates for callbacks about box2d HOT 6 CLOSED

I wasn't sure if HTML would work, and it clearly didn't.  Anyway, the URL is
http://www.codeproject.com/KB/cpp/FastDelegate.aspx

FastDelegate requires non-standard C++ as well as compiler specific 
implementations.
 Too much work for little gain.  boost::function style delegates would work, but
don't provide any performance advantages (only trade offs).

While FastDelegate is indeed nonstandard, it's widely supported by modern 
compilers.
 There's another one
(http://www.codeproject.com/KB/cpp/ImpossiblyFastCppDelegate.aspx) that's
standards-compliant but less-widely supported (ironically).  There's always a
possibility that the iPhone or Nintendo DS platforms might have issues, but 
their
compilers seem decent enough.  (Ultimately, a delegate is a simple thing: a 
"this"
pointer and a function address.  There's only so many ways to construct a 
virtual
function or a pointer to member...)

I've made use of FastDelegate on the DS in both ARM and THUMB modes (haven't 
tested
it using the home-brew environment though)

You can essentially implement your own delegates already.

True, though it isn't as efficient because it requires a third layer of 
indirection
(virtual function table, virtual function, and target method).  :)