From: Brian Candler <B.Candler@...>
Date: 2004-10-05T20:26:56+09:00
Subject: Re: [RCR] New [] Semantics

On Tue, Oct 05, 2004 at 07:38:01PM +0900, trans.  (T. Onoma) wrote:
> > Besides,
> >   a = a.succ
> > and
> >   a = a + 1
> > take almost identical amounts of time, since even '+ 1' involves a method
> > dispatch:
> >   a = a.send(:+,1)
> 
> With inc/dec modulo can be used. Something like:
> 
>   def member?(e)
>     return ( (((e + self.begin) % @increment) == 0) && self.between?(e) )
>   end

Erm, no I don't get that. You're declaring a 'member?' test for a class of
objects which support the methods '+', '%', 'between?' and '==' with some
particular semantics (they form a group?? IANAM), but presumably not
numbers.

Can you give an example of a class of objects for which your 'member?'
function is useful, but this one is not:

  def member?(e)
    return e >= self.begin and e <= self.end
  end
#or
  def member?(e)
    return e.between(self.begin, self.end)
  end

I also can't see what "x.between?(y)" is supposed to do, with a single
argument (y).

Regards,

Brian.