From: Tobias Cohen <me@...>
Date: 2009-11-19T08:38:01+09:00
Subject: Re: Inheriting from Object


On 19/11/2009, at 10:16 AM, Mike Stephens wrote:
> "Methods defined outside of any class ... are automatically defined as
> part of the Object class. Because every class automatically inherits
> from the Object class, these methods are therefore inherited by every
> class."
>
> When I tried this, it didn't work (ie write some methods and then
> declare a class and try and use those methods on new members of that
> class) . Ruby issues an error message - "private error
> called...(nomethoderror)".

It looks like these methods are defined as /private/ methods of  
Object, so you can't call them from outside of the object. For some  
reason, irb confusingly makes public methods instead, so I had to  
write a test program to find this out.

> It raises an interesting question. When you write methods outside of a
> specific class block, you are in the envelope of some top level class,
> so why aren't these methods added?

You are in the envelope of the "main" class, but Ruby has a special  
case for methods defined here - this thread is fairly informative:

http://groups.google.com/group/comp.lang.ruby/browse_thread/thread/7bb7b451a8f3cca7/98c4c62127b9d945

Tobias Cohen
http://tobiascohen.com/