From: Florian Frank <flori@...>
Date: 2004-10-05T20:11:52+09:00
Subject: Re: [RCR] New [] Semantics


On 05.10.2004, at 11:59, Brian Candler wrote:

> On Tue, Oct 05, 2004 at 06:19:09PM +0900, trans.  (T. Onoma) wrote:
>> I occurs to me that the angry villagers might be confused. The 
>> example of the
>> never ending
>>
>>   (0..(10.0/0)).member?(4)
>>
>> comes to mind. Why would this be an infinite loop? It must be trying 
>> to
>> generate the list before looking to see if 4 is in it (?)
>
> Yes, see adjacent thread. What it actually does is iterate all value 
> from
> start to end using succ, and set a flag to true when it finds a match 
> (but
> it doesn't break out of the loop when a match is found)

This seems the wrong thing to do. The documentation says:

---------------------------------------------------------- Range#member?
      rng.member?(val)   =>  true or false
------------------------------------------------------------------------
      Return +true+ if _val_ is one of the values in _rng_ (that is if
      +Range#each+ would return _val_ at some point).

I would think that it should return true, instead of going round in 
circles.
I can understand that include? was overridden, because there is a more
efficient way to check for inclusion in ranges and it makes a lot of 
sense for
ranges of Floats.

The Enumerable version works ok:

 >> Enumerable.instance_method(:member?).bind(0..(1.0/0)).call(4)
=> true

I would prefer getting rid of the overriden member? implementation
in range.c.

Florian Frank