Inheritance In a PHP Class and Object-Oriented Programming

Let’s talk about inheritance in PHP. First, here’s how you do it:

<?php
class Daddy {
    public function my_method() {
        echo "I'm the parent";
    }
}
class Son extends Daddy {
    
}
$child = new Son;
$child->my_method(); // This outputs "I'm the parent" from the parent class

The child is the class DOING the extending. The parent is the class BEING extended. And, the child inherits any public or protected properties and methods from the parent. This is why “Son” has no methods, but still outputs the results of my_method(). Because it inherited that method from Daddy.

But, private methods and properties are NOT inherited. So, this won’t work:

<?php
class Daddy {
    public function my_method() {
        echo "I'm the parent";
    }
    
    private function you_cant_haz() {
        echo "Only Daddy gets me!";
    }
}
class Son extends Daddy {
    
}
$child = new Son;
$child->you_cant_haz(); // This triggers a fatal error

You can also override inherited methods in the child. Like this:

<?php
class Daddy {
    public $var = "Call me Daddy! ";
    
    public function my_method() {
        echo $this->var;
    }
    
    private function you_cant_haz() {
        echo "Only Daddy gets me!";
    }
}
class Son extends Daddy {
    public $var = "Uh, that's creepy. No!";
    
    public function my_method() {
        echo $this->var;
    }
}
$parent = new Daddy;
$parent->my_method(); // This outputs "Call me Daddy!"
$child = new Son;
$child->my_method(); // This outputs "Uh, that's creepy. No!"

One example use case for this is WordPress widgets. When creating a new widget, your individual widget class extends WP_Widget to access and override its default methods. WordPress then does the “magic” of putting your widget together simply by you overriding the WP_Widget methods in your class.

Another example is the example OOP application shell I show you how to build in my object-oriented programming course. I give you a primer on MVC, which is obviously super popular right now, but is only one among many design patterns. But, I also show you another pattern I learned a few years back that I personally like better… and it involves some strategic inheritance like this. You can learn more about and enroll in my object-oriented programming course here.

Who else wants to build a thriving freelance business?

I’ve helped 39,413 other freelancers start and grow thriving freelance businesses. Are you next? Subscribe to my Freelance Secrets newsletter and I’ll show you how.

You might also like

Facebook
Twitter
LinkedIn
Reddit
Pinterest
John Morris

JOHN MORRIS

I’m a 15-year veteran of freelance web development. I’ve worked with bestselling authors and average Joe’s next door. These days, I focus on helping other freelancers build their freelance business and their lifestyles.

Who else wants to build a thriving freelance business?

I’ve helped 39,413 other freelancers start and grow thriving freelance businesses. Are you next? Subscribe to my Freelance Secrets newsletter and I’ll show you how.

Success Stories

Ready to add your name here?

Tim Covello

Tim Covello

75 SEO and website clients now. My income went from sub zero to over 6K just last month. Tracking 10K for next month. Seriously, you changed my life.

Michael Phoenix

Michael Phoenix

By the way, just hit 95K for the year. I can’t thank you enough for everything you’ve taught me. You’ve changed my life. Thank you!

Stephanie Korski

Stephanie Korski

I started this 3 days ago, following John’s suggestions, and I gained the Upwork Rising Talent badge in less than 2 days. I have a call with my first potential client tomorrow. Thanks, John!

Jithin Veedu

Jithin Veedu

John is the man! I followed his steps and I am flooded with interviews in a week. I got into two Talent clouds. The very next day, I got an invitation from the talent specialists from Upwork and a lot more. I wanna shout out, he is the best in this. Thanks John for helping me out!

Divyendra Singh Jadoun

Divyendra Singh Jadoun

After viewing John’s course, I made an Upwork account and it got approved the same day. Amazingly, I got my first job the very same day, I couldn’t believe it, I thought maybe I got it by coincidence. Anyways I completed the job and received my first earnings. Then, after two days, I got another job and within a week I got 3 jobs and completed them successfully. All the things he says seem to be minute but have a very great impact on your freelancing career.

Sarah Mui

Sarah Mui

I’ve been in an existential crisis for the last week about what the heck I’m doing as a business owner. Even though I’ve been a business for about a year, I’m constantly trying to think of how to prune and refine services. This was very personable and enjoyable to watch. Usually, business courses like this are dry and hard to get through…. repeating the same things over and over again. This was a breath of fresh air. THANK YOU.

Waqas Abdul Majeed

Waqas Abdul Majeed

I’ve definitely learnt so much in 2.5 hours than I’d learn watching different videos online on Youtube and reading tons of articles on the web. John has a natural way of teaching, where he is passionately diving in the topics and he makes it very easy to grasp — someone who wants you to really start running your business well by learning about the right tools and implement them in your online business. I will definitely share with many of the people I know who have been struggling for so long, I did find my answers and I’m sure will do too.

Scott Plude

Scott Plude

I have been following John Morris for several years now. His instruction ranges from beginner to advanced, to CEO-level guidance. I have referred friends and clients to John, and have encouraged my own daughter to pay attention to what he says. All of his teachings create wealth for me (and happiness for my clients!) I can’t speak highly enough about John, his name is well known in my home.

Sukh Plaha

John is a fantastic and patient tutor, who is not just able to share knowledge and communicate it very effectively – but able to support one in applying it. However, I believe that John has a very rare ability to go further than just imparting knowledge and showing one how to apply it. He is able to innately provoke one’s curiosity when explaining and demonstrating concepts, to the extent that one can explore and unravel their own learning journey. Thanks very much John!

Mohamed Misrab

Misrab Mohamed

John has been the most important person in my freelance career ever since I started. Without him, I would have taken 10 or 20 years more to reach the position I am at now (Level 2 seller on Fiverr and Top Rated on Upwork).

Who else wants to build a thriving freelance business?

I’ve helped 39,413 other freelancers start and grow thriving freelance businesses. Are you next? Subscribe to my Freelance Secrets newsletter and I’ll show you how.