Re: [boost] [RFC] Generic non-intrusive Visitor pattern utility

From: Lassi A. Tuura (lassi.tuura_at_[hidden])
Date: 2008-01-11 10:02:44

Hi,

FWIW what's discussed here is known as multi-methods in some corners  
of programming world.  A multi-method with one "virtual" argument  
would simply be a virtual function outside a class, which is probably  
what the original poster was looking for.  Some relatively dynamic  
languages, e.g. clos and dylan, support multi-methods as a native  
concept.

I believe there have been past discussions on multi-methods in  
boost.  I believe at least Jesse Jones was involved in one discussion  
thread around September 2004.

I implemented multi-methods for C++ long time ago as a library.   
We've used them in one data visualisation project, but not really  
otherwise.  See the links below for some documentation and examples.   
I doubt that particular library in the form boost would like to have,  
but perhaps it gives you ideas to take further.  Note that the code  
is GPLed.

http://cmslxr.fnal.gov/lxr/source/Iguana/Utilities/classlib/utils/ 
MultiMethod.h#093
http://cmslxr.fnal.gov/lxr/source/Iguana/Utilities/test/utils/ 
MultiMethod01.cpp
http://cmslxr.fnal.gov/lxr/source/Iguana/Utilities/test/utils/ 
MultiMethod02.cpp
http://cmslxr.fnal.gov/lxr/source/Iguana/Utilities/test/utils/ 
MultiMethod03.cpp

Lassi