An eigenclass in Ruby, also known as a singleton class or metaclass, is a hidden, anonymous class that is automatically created by Ruby for each object. It is where Ruby stores methods that are defined on a single object, known as singleton methods. These methods are not shared with other instances of the same class but are unique to the specific object.
When you define a method on an object itself, rather than on the object's class, Ruby places that method in the object's eigenclass. This allows the method to be called on that particular object without affecting other instances of the class. The eigenclass is part of Ruby's object model and is used to support the object-oriented feature of adding behavior to individual objects at runtime.
Eigenclasses are not directly accessible in the same way that regular classes are, but Ruby provides a syntax for opening the eigenclass of an object and adding methods to it. This is done using the class << object syntax. Methods added in this context are singleton methods of the object.
The concept of eigenclasses is fundamental to understanding Ruby's metaprogramming capabilities, as it allows developers to dynamically define methods on objects and classes at runtime, providing a powerful tool for creati...
