Ruby Class Methods: Class and Instance Methods in Ruby

One of the most important aspects of writing the ruby classes is to understand the difference between the class methods and the instance methods & we’d like to cover this difference in this post of ours. First off, the method that resides at the class level is said to be the class method and the one that resides at an object level is said to be the instance method. To make it easier to relate with — for the developers, the methods that are called on a class are the class methods, and the ones that are called on an instance of a class, are the instance methods.

When working on Ruby, you must know that classes are objects too, and therefore, the methods that are defined as the class methods correspond specifically only to the objects that define those classes.
For example, if we define my_class_method in a class called Test, my_class_method will only correspond to the object called Test, and this Test is nothing but an example of a built-in ruby class called as ‘Class’.

When to use a class method?

A class method is a piece of functionality independent of any particular instance, rather, it is the one that just belongs to a class. The class method is used for the functionality that is not specific to any instance of a class.

When to use the Instance Methods?

Instance methods are used when you are required to act on a specific instance of a class. When you need to introduce functionality that corresponds to the identity of an instance, you should use the instance method.

It is important to understand this seemingly subtle difference between where to use a class method and where to employ an instance method because, in absence of a clear understanding of this, your object-oriented design can go wrong. So, this leads you to often encounter cases where both class methods and instance methods have been wrongly used in place of each other. The encapsulation and modeling attributes of the object-oriented design are the key elements of its success. So, it should be kept in mind that when the functionality to be implemented corresponds to an object, the instance methods need to be employed. At the same time, it is also important to know whether the functionality that’s being implemented is in line with the specific instance of the object or not.




Ruby on Rails Development Company

Love podcasts or audiobooks? Learn on the go with our new app.

Recommended from Medium

How to do Unit Testing in Flask and find Code Coverage

Accept RESTful API requests with your GraphQL/Express Server

Golang gRPC — Part 2 — Simple chat application with gRPC

Zebrunner, Inc. has announced an official merger with Zafira reporting portal

🏦 第20週 — 自動化獲利與自動執行銀行

Configure FreeRADIUS to use MySql on Linux.

Angela: From Admin to Software Developer in Rotterdam

Boosting Parallel INSERTs

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store


Ruby on Rails Development Company

More from Medium

We are nature , think positive it affects chemistry .

The Feisty Forager: Sassafras

Communication and the 10 C’s

Happy Birthday to Me!