From: Friedrich Dominicus <frido@...>
Date: 2002-09-12T18:59:55+09:00
Subject: Re: Multimethods (was Re: Larry Wall's comments on Ruby)

Dan Sugalski <dan@sidhe.org> writes:

> At 12:57 AM +0900 9/12/02, Christoph wrote:
> >"Dan Sugalski"  wrote in
> >....
> >>  That's pretty much multimethods. They're terribly useful, as they cut
> >>  out a lot of checks for the second type in methods. (Checks which
> >>  tend to be slow, error prone, and missing stuff)
> >
> >Thanks Dan, for making such an eloquent case for multimethods.
> >Personal I cannot image (surely an effect of being single and
> >simple minded;-) how their use could be less complex then the
> >alternatives like Rubys coerce framework  or double-dispatch ..
> 
> Their big problem is that they introduce methods that don't live in
> any class. If you have the methods:
> 
> 
>     add(int, num)
>     add(num, int)
>     add(bignum, int)
> 
> those three, while methods, don't live in any class, so if you did:
> 
>     foo.add(bar)
sorry any from the above has nothing to do with this one. 
you could have
a foo.add(int,num)
 foo.add(num,int)
..
and yo can have a foo.add(bar). 

> 
> you may well not be executing the add method defined in the foo
> class--you may be executing the one defined in the bar class, or the
> baz class, or maybe in some standalone code you loaded.
Well I would not expect foo.add to comply to any from the functions
above.

Regards
Friedrich