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method overloading in ruby

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method overloading in programing refers to invoking different behavior of a method of class depending on its arguments. Making it simpler, you can say that a class can have more then one method with the same name, but with different argument i,e different signature of the method.

You can implement different signature of method in any of the below way:

1 : Arguments with different data types, eg: method(int a, int b) vs method(String a, String b)
2:  Variable number of arguments, eg: method(a) vs method(a, b)

Let’s try to do method overloading in ruby.

create a overloading_demo.rb file and add below lines to it

class Person

  def print_details(name)
    "Hey My Name is #{name}"

  def print_details(name,age)
    "Hey My Name is #{name} and #{age}"

person1 =
puts person1.print_details("arun")
puts person1.print_details("arun",25)

So, with overloading, you expect to get different message detail when you pass only name, and when pass both name and age.

Let see what we get by running the above code.

$ ruby overloading_demo.rb
overloading_demo.rb:7:in `print_details’: wrong number of arguments (1 for 2) (ArgumentError)

So, you can see that, overloading not happening here. ruby expecting print_details to have two argument, but since in the first call, you passed only one argument, it throws error. So we can say that:

Ruby do not support method overloading

In ruby there can be only one method with a given name. If there is multiple methods with the same name,the last one prevail i,e the last method will be invoked when called.

In above case, the last print_details method have two argument, so this will prevail and any call to print_details will expect two arguments. Since the first call to print_details passing only one argument, you are getting the above error.

But why ruby not support method overloading, when it is known feature in other language like C.

This is because  “Overloading” is a term that simply doesn’t even make sense in Ruby. It is basically a synonym for “static argument-based dispatch”, but Ruby doesn’t have static dispatch at all. So, the reason why Ruby doesn’t support static dispatch based on the arguments, is because it doesn’t support static dispatch, period. It doesn’t support static dispatch of any kind, whether argument-based or otherwise.

At the beginning, I have mentioned two way in which method overloading takes place : one when argument type differ and other when number of argument differ.

But ruby is dynamic typed language i,e type of the method argument is evaluated at the run time. You can see that, you have not specified the type of argument while defining print_details method, it is decided at run time so… print_details(int name,int age) and print_details(string  name, string age) is same in ruby. for variable no of argument implementation print_details(name, age=25) and print_details(name) definition is same, as they can be invoked with single argument.

Due to these issues ruby get rid of method overloading. Personally, I never felt its harming me in any way. In any case if you want to execute different behavior  for a method based on argument, you can write your own customize code. Lets modify our overloading_demo.rb to get what we want, without method overloading.

class Person

  def print_details(*args)
    case args.size
    when 1
      "Hey My Name is #{args[0]}"
    when 2
      "Hey My Name is #{args[0]} and #{args[1]}"


person1 =
puts person1.print_details("arun")
puts person1.print_details("arun",25)

No when you run the above code you can get the result you expect from overloading

$ ruby overloading_demo.rb
Hey My Name is arun
Hey My Name is arun and 25

Hope, you now have clear idea of method overloading in ruby


Author: arunyadav4u

over 7 years experience in web development with Ruby on Rails.Involved in all stage of development lifecycle : requirement gathering, planing, coding, deployment & Knowledge transfer. I can adept to any situation, mixup very easily with people & can be a great friend.

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