Ruby craziness: Class vs Object?

Question

I just started playing with JRuby. This is my first ruby post. I had a hard time understanding classes vs objects in Ruby. It doesnt mean like what classes & objects in

Answer 1

One of the answers mentions this:

Basically the key thing to understand is that every class is an instance of the Class class and every class is a subclass of Object. So every class is an object in the sense that it is an instance of a subclass of Object, i.e. Class.

I just want to word it differently for those who have a little brain twist. First ask yourself: What is an instance in programming? And what is a subclass in programming? An instance is just a realized variation of a blueprint (the Class). A subclass is simply a class (blueprint) that inherits from another class (blueprint). So when you create a new class:

class Apple
end

Apple is an instance of Class, that is, it is a realized variation of the blueprint. It takes the blueprint and fills in the details (methods and variables) with its own variation. Well, the blueprint inherits from another blueprint, which is Object. So every class is an instance of Class, which is a subclass of Object.

class A 
end
A.superclass  
=> Object     
A.class  
=> Class

Note Class has Module in its inheritance chain (Module included in Class as a mixin perhaps since Class's parent is Object?).

A.is_a?(Module)
 => true  

Instances (A.new) of class A will have their own realized variations of A. But they are object instances. So we must distinguish class instances (e.g. class A end) and object instances ( a = A.new). Object instances have a different inheritance chain. They are a realized variation of a class instance blueprint, not a variation of class Class.

This means in their inheritance chain is not Class or Module. But rather other object instances, so if A has object instances and B has object instances and A inherits from B, when we instantiate a new object instance of A, this instance will have B instances in its inheritance chain.

They will also inherit from Object, since everything in Ruby inherits from Object.

a = A.new
 => # 
a.is_a?(Class)
 => false 
a.is_a?(Module)
 => false 
a.is_a?(Object)
 => true 

And this is the best way to think about it all. Do not go too deep with your thinking. Accept this as I have written it.