Ruby’s singleton methods are the methods that can be defined for a specific object only i.e. it works for a single object. These kinds of methods belong to the singleton class or eigenclass and are available exclusively for a single object, unlike the other methods which are available for all the instances of the class.
This feature is more useful where there is a need for the object to possess some unique behavior or methods which the other objects of the class do not own.
def Obj.GFG # Method body end
Here, the GFG is a singleton method and Obj is an object.
The concept of Singleton methods can be understood by the following examples:
Singleton Method Example Invoke from train object: There are many wheels Invoke from car object: There are four wheels
It can be observed that the method wheels have been redefined for the car object of Vehicle class. This wheels method is nothing but a singleton method that shows different behavior for the car.
Singleton Method Example: Invoke from the object(o1): 13 Invoke from the object(o2): Size does not matter
Singleton method can be defined for the objects which belong to library classes such as String. Instead of printing the size of Object o2, the above code is printing “Size does not matter!” because this is the return value of the o2.size method.