From: Saynatkari <ruby-ml@...>
Date: 2005-04-19T14:45:31+09:00
Subject: Re: - E03c - The Ruby Object Model (Revised Documentation)


Le 19/4/2005, "Ilias Lazaridis" <ilias@lazaridis.com> a �crit:
>Jim Weirich wrote:
>> On Monday 18 April 2005 11:34 pm, Ilias Lazaridis wrote:
>>
>>>>There is another evident mistake in your UML diagram. Object doesn't
>>>>inherit from nil, nil is a literal and an instance of NilClass which
>>>>inherit from Object.
>>>
>>>you are wrong:
>>>
>>>irb(main):001:0> Object.superclass
>>>=> nil
>>
>> The documentation for superclass clearly states that it returns the superclass
>> of its target, or nil.
>>
>> In this case it returns nil because Object does not have a superclass, i.e. it
>> does not inherit from anything.
>
>In context of an Language Object Model:
>
>Object inherits from "nil".

Er, no. Object does not inherit. As was pointed out to
you, #superclass just happens to return nil to signify
there is no superclass.

>"nil" is represented by an _instance_ of class "NilClass".
>
>I've drawn this instance "nil" into the diagram.
>
>[possibly it will be removed with the next revision]
>
>-
>
>Nil is a terribly confusing topic, thus I would prefere to keep is out
>of the currect topic.

Why is it confusing? nil is 'nothing'.

>You can review an old thread about smalltalk's Nil:
>
>comp.lang.smalltalk > ST - The Loneliness of Nil
>http://groups-beta.google.com/group/comp.lang.smalltalk/msg/f7f017a49e6268

>http://lazaridis.com

E

--
template<typename duck>
void quack(duck& d) { d.quack(); }