Singleton method/class in Ruby

For example, we have many instances of class String and we want to define some special methods for only a specific instance, but don’t want the others (same class) have these methods. Ruby supports us to do this by the singleton class.

• Is used for extending methods for an specific instance (note thatmodule, class also are instances of Module, Class)
• To get the instance’s singleton class, call [instance].singleton_class
• To see which function is belonged to the singleton class called [instance].singleton_methods
• The singleton class could also have its singleton class

References

• https://stackoverflow.com/a/61381826/1142154
• https://devalot.com/articles/2008/09/ruby-singleton
• https://medium.com/@leo_hetsch/demystifying-singleton-classes-in-ruby-caf3fa4c9d91