From: Robert Klemme <shortcutter@...>
Date: 2007-10-31T21:03:48+09:00
Subject: Re: Code to DRY

2007/10/31, Michel Demazure <michel@demazure.com>:
> Robert Klemme wrote:
> > 2007/10/31, Michel Demazure <michel@demazure.com>:
> >> >>   end
> >> >> end
> >> >
> >> > And instead of #le?, why not #<, #==, #>, #<=>?
> >>
> >> #< looks good. Thanks.
> >
> > Also keep attention to module Comparable
> > http://www.ruby-doc.org/core/classes/Comparable.html
> >
> > Basically you need to only implement <=> and get all other operators for
> > free.
> >
> > Btw, what do you need min and max for?
> >
> > Kind regards
> >
> > robert
>
> Robert,
>
> Actually, I have partial orders ("préordre" in french) and not orders
> ("ordre total" in french), so <=> does not work well. For instance, you
> can have a.le?(b) and b.le?(a), but not a = b. Or neither a.le?(b), nor
> b.le?(a). For instance a.lt?(b) is "a.le?(b) and not b.le?(a)" but not
> "a.le?(B) and a != b".

Ah, I see.  I wasn't aware of this.  In that case it's probably also
not a good idea to use <, > etc. to avoid confusion. Do you use some
kind of topological sort then?

> I need min and max for semantic reasons, analogous to Scott's semantics
> for programming languages : 'min' is something like 'undefined'
> (definitely less than 'defined with value nil' for instance) and 'max'
> is something like 'overdefined' or 'impossible'. All this for some try
> at a "fuzzy knowledge" management program...which actually works quite
> well!

I still do not know how you use min and max but it certainly sounds
interesting! :-)

Kind regards

robert

-- 
use.inject do |as, often| as.you_can - without end