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Ruby OOP (Object-Oriented Programming)

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Objects

Objects, Classes, and Methods Objects Are Instances of Classes Objects Have Methods Calling Methods Passing Arguments Listing and Chaining Methods Predicate Methods Bangs Quiz on Objects Exercise 1: Chaining

Blocks

What Are Blocks Alternative Block Syntaxes Block Arguments Block Return Values Exercise 1: Extract Even Elements from an Array Inversion of Control Iterators Quiz on Blocks Exercise 2: Even Reversed Exercise 3: Sum the Rows of a Matrix Exercise 4: Print the Output Using Nested Arrays

Conditionals

What Are Conditionals?Shorthand Syntax Conditionals Return Values Nothingness and the Truth Quiz on Conditionals Exercise 1: Number of Days in a Month

Writing Classes

Getting Started with Classes

Defining and Instantiating Classes

Defining Instance Methods

Initializing Objects

Instance Variables

Class Variables

Attribute Readers

Attribute Writers

State and Behavior

Interacting Objects

Object Scope and Self

Quiz on Classes

Exercise 1: Make a Rectangle Class

Exercise 2: On Class Methods

Project

Mini project 1

Conclusion

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Defining and Instantiating Classes

Defining and Instantiating Classes

Learn how to define our own classes and create class instances.

Let’s start by creating a Calculator class and adding some methods to it, step by step.

In Ruby, we define a class like this:

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Ruby

class Calculator
end

That’s all. It’s not a very useful class because it’s completely empty, but it’s a class.

Remember: A class is defined using the class keyword, a name, and the end keyword.

Use capital letters to define classes

Notice also that the class has the name Calculator, which starts with an uppercase letter. In Ruby, this is required, and we’d get an error if we tried to define a class called ...