Re: [boost] Boost.Multimethod proposal

Subject: Re: [boost] Boost.Multimethod proposal
From: Jeffrey Bosboom (jbosboom_at_[hidden])
Date: 2009-08-22 23:01:34

Edward Diener wrote:
> What is a practical use for multi-methods ?

Multimethods (assuming this library uses the term as it's commonly 
understood) are like virtual functions that are dispatched on the 
dynamic types of their arguments as well as the type of *this.  You can 
get this effect through double dispatch, but it requires a bit of 
plumbing and requires two virtual calls (which for some people is a 
large amount of overhead).  (Of course, multimethods have overhead too.)

There's a Stroustrup et al paper on the feasibility of adding 
multimethods to C++ here: http://research.att.com/~bs/multimethods.pdf . 
I'm not sure how relevant it is to the current proposal, but it contains 
information on an experimental implementation that was faster than 
double dispatch.

--Jeffrey Bosboom