From: Brian Candler <B.Candler@...>
Date: 2004-10-06T18:15:53+09:00
Subject: Re: Range behavior (Re: [RCR] New [] Semantics)

On Wed, Oct 06, 2004 at 11:18:50AM +0900, trans.  (T. Onoma) wrote:
> > Range serves as both continuous and discrete interval of values.
> > 'member?' treat it as discrete, whereas 'include?' treat it as
> > continuous.
> 
> irb(main):001:0> a = 0..2
> => 0..2
> irb(main):002:0> a.include?(1)
> => true
> irb(main):003:0> a.include?(1.5)
> => true
> irb(main):004:0> a = a.to_a
> => [0, 1, 2]
> irb(main):005:0> a.include?(1)
> => true
> irb(main):006:0> a.include?(1.5)
> => false
> 
> :(  

Are you saying: get rid of Array#include? and Enumerable#include? (for 2.0)?

If so I would agree. Or at least, very clearly document Enumerable#include?
and Enumerable#member? as being intended for different purposes, whereas
right now they are documented as being aliases, implying they are always
interchangeable.

This would give a duck-typing convention of

  #member?(x)   -- x is an instance of a discrete set of values
  #include?(x)  -- x is contained within a continuous interval

Regards,

Brian.