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I've done some work with functions in Javascript, and thought that a Method was the Ruby name for the same. I recently did a technical interview and the interviewer was trying to help me debug by explaining how Methods were part of a class, and that it's an OOP thing.

I can't spot a functional difference between a Method and an equivalent Function, so I don't see what classes have to do with it.

Can you explain the whole 'Methods are part of a class' thing and why it matters? How can a Method be part of a class? Class as in an integer or a string?

The interviewer believed it would help, but it seems like a tiny technicality more than something useful.

Can you explain the whole 'Methods are part of a class' thing and why it matters? How can a Method be part of a class? Class as in an integer or a string?

Let's say you have two classes, Apple and Cake. Let's assume that when you sell an apple, it has a tax rate of 10%, and cake 20%. By splitting the methods into individual classes, we can define a different method for 'price_with_tax' to each class:

class Apple < ApplicationRecord

  def price_with_tax

    self.price * 1.1

  end

end



class Cake < ApplicationRecord

  def price_with_tax

    self.price * 1.2

  end

end

In javascript we wouldn't be able to do this, and would need to have 2 methods, 'add 10% tax' and 'add 20% tax'. By structuring the methods as we have, we're able to do:

apple = Apple.find(1)

cake = Cake.find(1)

cake.price_with_tax

apple.price_with_tax

Methods are generally something that a class can do,
class MailClient(for example) might have methods such as sendMail, getMail, forwardMail, etc. In OOP, methods should for the most part be something that a class can do.

    MailClient.getMail();

The above code can be conceptualized as telling the class to invoke its getMail() behavior.

You may think of this in real-life terms such as:

Dog.bark();

Objects have behavior and attributes, the behaviors are the methods.

In OOP:

Class is like a blueprint/template. It has properties, methods etc. An object can be created with it. So an object can call method in class.
Usually a method is created to perform an operation.

Example:

// a demo class

public class Animal{

    // a method

    public void sound(){

        // do something...

    }



    // main class, we create an object and call sound() method

    public static void main(String args){

        Animal dog = new Animal();     // create an object so that we can use the method

        dog.sound();    // method call

    }

}