# Inheriting from Object **URL:** \ **Category:** Ruby\ **Created:** [November 19, 2009, 12:14am UTC](https://www.ruby-forum.com/t/inheriting-from-object/179173 "2009-11-19T00:14:21Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![mschwab](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/59ef9b/32.png) [@mschwab](https://www.ruby-forum.com/u/mschwab)\ **Post date:** [November 19, 2009, 12:14am UTC](https://www.ruby-forum.com/t/inheriting-from-object/179173/1 "2009-11-19T00:14:21Z")
I’m just working through Ruby Visual Quickstart Guide by Larry Ullman, which is quite an enjoyable book (so far). In it he has this : “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)”. I lodged a question on Larry’s web site, and to his credit he replied in due course. He said “I’m sorry: what I wrote probably isn’t clear there. Every object inherits the methods in the original Object, but they don’t inherit methods created in situations like this. Sorry for the confusion!” 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? ---
**Author:** ![mschwab](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/59ef9b/32.png) [@mschwab](https://www.ruby-forum.com/u/mschwab)\ **Post date:** [November 19, 2009, 12:38am UTC](https://www.ruby-forum.com/t/inheriting-from-object/179173/2 "2009-11-19T00:38:17Z")
On 19/11/2009, at 10:16 AM, Mike S. 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](http://groups.google.com/group/comp.lang.ruby/browse_thread/thread/7bb7b451a8f3cca7/98c4c62127b9d945) Tobias Cohen > **[Tobias Cohen](https://tobico.net/)** > > Web + game developer ---
**Author:** ![mschwab](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/59ef9b/32.png) [@mschwab](https://www.ruby-forum.com/u/mschwab)\ **Post date:** [November 19, 2009, 12:45am UTC](https://www.ruby-forum.com/t/inheriting-from-object/179173/3 "2009-11-19T00:45:53Z")
On Nov 18, 6:16 pm, Mike S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > ## class) . Ruby issues an error message - "private error so why aren’t these methods added? > > Posted viahttp://www.ruby-forum.com/. xeno@Clover:~/projects$ ruby -e “puts class \<\< self; self; end.inspect” #\ This says to me that top level is instance of class Object (which mixes in Kernel), so methods defined in top level will be added to that object’s singleton class, not the base Object class. However this is just a guess inspired by your question; I await the actual answer to this. ---
**Author:** ![mschwab](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/59ef9b/32.png) [@mschwab](https://www.ruby-forum.com/u/mschwab)\ **Post date:** [November 19, 2009, 12:46pm UTC](https://www.ruby-forum.com/t/inheriting-from-object/179173/4 "2009-11-19T12:46:56Z")
Mike S. wrote: > 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? They are added, they are just private. You have to call them as private methods. They are made private because they simulate what functions are used for in other languages. You can call them from anywhere but only without a receiver. If you want to create methods for classes, that are supposed to be called on receivers, it’s better to inherit from a class, write a module and include it in your class, or even reopen the class and add the methods directly. I always thought it was pretty neat how consistently Ruby uses its OOP design to implement all the features people have come to expect from modern languages. ---
**Author:** ![mschwab](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/59ef9b/32.png) [@mschwab](https://www.ruby-forum.com/u/mschwab)\ **Post date:** [November 19, 2009, 12:50am UTC](https://www.ruby-forum.com/t/inheriting-from-object/179173/5 "2009-11-19T00:50:34Z")
On Nov 18, 6:43 pm, pharrington [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > part of the Object class. Because every class automatically inherits > > Every object inherits the methods in the original Object, but they don’t > > end.inspect" > > #\ > > This says to me that top level is instance of class Object (which > mixes in Kernel), so methods defined in top level will be added to > that object’s singleton class, not the base Object class. However this > is just a guess inspired by your question; I await the actual answer > to this. Ignore all this: I don’t understand Ruby.