Lesson 15 - Interfaces and abstract classes in PHP

In the previous lesson, Interfaces in PHP, we introduced you to interfaces. Today, we are going to finish up with the theoretical part and start working with what are known as abstract classes.

By-passing multiple inheritance

As you already know, PHP can only inherit from a single class. Regardless, before we move on, let's get to the root of dealing with having to inherit from more than one object in a complex application.

Class hierarchy

If we want an object to inherit from two classes, we'd have to create a class hierarchy and inherit the object multiple times (Human -> Programmer -> PhpProgrammer):

class Human
{
        //...
}

class Programmer extends Human
{
        //...
}

class PhpProgrammer extends Programmer
{
        //...
}

In this case, PhpProgrammer technically inherits from both the Human and Programmer classes.

Interface delegating

In order to bypass the lack of multiple inheritance, we would have to use interfaces

...End of the preview...

Premium article

ict.social is a large database made up of manuals and tutorials, whose main goal is to provide high-quality IT education to everyone. We started out in the Czech republic, where we display roughly a million articles per month and receive plenty of gratitude from our users. Thanks to our successful establishment, we are now bringing these articles to the rest of the world.

Although we are trying to keep our content free of charge, maintaining the site is a huge effort for everyone involved. Therefore, some content (exercises and more advanced material) costs network points. Don't worry, they're really cheap :)

Article description

Requested article covers this content:

In this lesson, we'll keep going with interfaces as well as introduce you to abstract classes. You'll learn to implement and delegate interfaces.

Limited offer: Learn all knowledge and save money

	Buy articles and tests separately one by one	~~200 points~~
	Buy the course including all articles and features for an exclusive price	170 points
Currently, you have		0 points
By buying this exclusive package, you'll have access to all 34 articles in this course including exercise submitting while saving $2.70. This offer is limited for the first articles only with an additional exclusive 15% discount.
You gain 170 points for adding an article to the site, or for		~~$18.00~~ $15.30

Buying this article gives you unlimited access to it forever. You will learn some more and help us keep giving our site maintenance which helps you and others get better futures. It's a win-win.

This article is licensed :Premium, by buying this article, you agree with the terms of use.

You gain points by supporting our network. This is done by sending a helpful amount of money to support the site, or by creating content for the network.

You can get points immediately using:


Credit card	SMS	Wire transfer

Article has been written for you by David Capka

The author is a programmer, who likes web technologies and being the lead/chief article writer at ICT.social. He shares his knowledge with the community and is always looking to improve. He believes that anyone can do what they set their mind to.

The author learned IT at the Unicorn College - a prestigious college providing education on IT and economics.

Activities (10)

	To access the article, you need	10 points
Currently, you have		0 points
You gain 10 points for adding an article to the site, or for		$0.90