Gain insights into Ruby development with 78 tasks tailored for beginners and experienced coders. Explore object-oriented concepts, debug programs, and advance your freelance coding career.

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This self-study course written as a book is your first step towards making money by coding and programming from home, and having fun doing it. You will understand how the Ruby language works, and establish a foundation for being a successful freelance developer. This course gives you not only technical detail, but presents knowledge in a friendly format, understandable by all ages, providing a thorough explanation of modern concepts for absolute beginners.

In this course you will find 78 easy to follow tasks, so even people without any programming skill can solve them. Beginners will learn how to create, debug, and understand programs in Ruby. Those who are already familiar with the language will rediscover object-oriented concepts, memory organization, find career advice, and save the planet from a nuclear apocalypse.

Ready to dive into one of the most influential and demanding third generation programming languages? Let's tune in!

The Handbook for Ruby Developers

# What is polymorphism
There are some intricate definitions in object-oriented programming. However, not all programmers  know what polymorphism and duck typing are, or what the difference is between the two. It happens because programming practice is often easier than theory.
 
The term **polymorphism** comes from the Greek roots *poly*, meaning “many”, and *morphe*, meaning “form”. 
 
According to Wiktionary, polymorphism is  “The ability to assume different forms or shapes” while biologically it means, “The coexistence, in the same locality, of two or more distinct forms… not connected by intermediate gradations”.That’s rather interesting, because we can see *“distinct coexistence”* and *“not connected”* simultaneously in polymorphism

The following joke can illustrate polymorphism:

Father: Son, go and get Red Label.
Son: 750ml or 1 liter?
Mother: Son, go and get Red Label.
Son: 500 grams or 1 kg?

"Father" object assumes "Red Label" to be a whiskey, while "mother" object assumes "Red Label" to be cheese. Basically, the method ("Son") _changes_ based on the type of object it was called upon.



# Example of polymorphism

Let’s discuss an example from programming. A commander sends a command `obj.send(:sit)` to different objects. A programmer would say every object has the same interface. The objects are different, but they all receive a command `obj.send(:sit)` sent by a commander and didn’t raise any error.
 
A statically-typed language programmer would define an interface for that . Here is a C# example:


```csharp
interface IListener {
    void Sit();
}

class Dog : IListener {
    public void Sit() {
        // ...
    }
}

class Human : IListener {
    public void Sit() {
        // ...
    }
}
```

Learn what is polymorphism and duck typing in Ruby language.

Before We Begin

First Steps

Fundamentals of Ruby

Conditional Statements

Operators and Methods

Arrays

Hash

Fun with Object Oriented Programming

Debugging in Ruby

Ruby Version Manager

Testing Ruby Programs

Wrap Up!

Appendix

Duck Typing and Polymorphism

What is polymorphism