0.0 Introduction to Objects

Everything is an object

We will begin our journey with objects.

In Ruby, just like in real life, our world is filled with objects. Everything is an object - integers, characters, text, arrays - everything.

To make things happen using Ruby, one always puts oneself in the place of an object and then has conversations with other objects, telling them to do stuff.

Roleplaying as an object in your program is an integral part of object-oriented programming. To know which object you are at the moment, one may use the keyword self.

Try it for yourself:

Example Code:

Output Window

As you can see, if you don't specify which object you are, you automatically play the role of the main object that Ruby provides us by default.

We'll delve into how one can play the role of different objects and why this is useful a little further down the line.

Talking to objects

One object interacts with another by using what are called methods. More specifically, one object "calls or invokes the methods" of another object.

In the example below, we call the method even? on the object that is the number 2 by placing a period (.) after the object, then adding in the name of the method we want to invoke.

Example Code:

Output Window

Invoking a method on an object inevitably generates a response. This response is always another object. Calling the method next on the object 1 has it give us the next consecutive value, 2.

One may also chain method invocations by simply adding more periods and method names sequentially - each method in the chain is called on the result of the previous method. Go on and try it by invoking next twice on 1 to get 3.

The results you're looking at are the consequence of running a series of tests against your input to validate it. If you see results coloured red, this means one or more tests failed. Green means you're good to go.

Congratulations, guest!

% of the book completed


This lesson is Copyright © 2011-2024 by Sidu Ponnappa and Jasim A Basheer