Object-Oriented PHP for Beginners
For many PHP programmers, object-oriented programming is a frightening concept, full of complicated syntax and other roadblocks. As detailed in my book, Pro PHP and jQuery, you’ll learn the concepts behind object-oriented programming (OOP), a style of coding in which related actions are grouped into classes to aid in creating more compact, effective code.
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Understanding Object-Oriented Programming
Object-oriented programming is a style of coding that allows developers to group similar tasks into classes. This helps keep code following the tenet «don’t repeat yourself» (DRY) and makes it easy to maintain.
One of the major benefits of DRY programming is that, if a piece of information changes in your program, usually only one change is required to update the code. One of the biggest nightmares for developers is maintaining code where data is declared over and over again, meaning any changes to the program become an infinitely more frustrating game of Where’s Waldo? as they hunt for duplicated data and functionality.
OOP is intimidating to a lot of developers because it introduces new syntax and, at a glance, appears to be far more complex than simple procedural, or inline, code. However, upon closer inspection, OOP is actually very straightforward and is ultimately a simpler approach to programming.
Understanding Objects and Classes
Before you can get too deep into the finer points of OOP, a basic understanding of the differences between objects and classes is necessary. This section will go over the building blocks of classes, their different capabilities, and some of their uses.
Recognizing the Differences Between Objects and Classes
Right off the bat, there’s confusion in OOP: seasoned developers start talking about objects and classes, and they appear to be interchangeable terms. This is not the case, however, though the difference can be tough to wrap your head around at first.
A class, for example, is like a blueprint for a house. It defines the shape of the house on paper, with relationships between the different parts of the house clearly defined and planned out, even though the house doesn’t exist.
An object, then, is like the actual house built according to that blueprint. The data stored in the object is like the wood, wires, and concrete that compose the house: without being assembled according to the blueprint, it’s just a pile of stuff. However, when it all comes together, it becomes an organized, useful house.
Classes form the structure of data and actions and use that information to build objects. More than one object can be built from the same class at the same time, each one independent of the others. Continuing with our construction analogy, it’s similar to the way an entire subdivision can be built from the same blueprint: 150 different houses that all look the same but have different families and decorations inside.
Structuring Classes
The syntax to create a class is pretty straightforward: declare a class using the class keyword, followed by the name of the class and a set of curly braces ( <> ):
Object-Oriented PHP With Classes and Objects
Sajal Soni Last updated Dec 15, 2022
In this article, we’re going to explore the basics of object-oriented programming using PHP classes.
We’ll start with an introduction to classes and objects, and we’ll discuss a couple of advanced concepts like inheritance and polymorphism in the latter half of this article.
What Is Object-Oriented Programming (OOP)?
Object-oriented programming, commonly referred to as OOP, is an approach which helps you to develop complex applications in a way that’s easily maintainable and scalable over the long term. In the world of OOP (to create object in PHP), real-world entities such as Person , Car , or Animal are treated as objects. In object-oriented programming, you interact with your application by using objects. This contrasts with procedural programming, where you primarily interact with functions and global variables.
In OOP, there’s a concept of «class«, which is used to model or map a real-world entity to a template of data (properties) and functionality (methods). An «object» is an instance of a class, and you can create multiple instances of the same class. For example, there is a single Person class, but many person objects can be instances of this class— dan , zainab , hector , etc.
The class defines properties. For example, for the Person class, we might have name , age , and phoneNumber . Then each person object will have its own values for those properties.
You can also define methods in the class that allow you to manipulate the values of object properties and perform operations on objects. As an example, you could define a save method which saves the object information to a database.
Let’s keep diving in to learn how to create objects in PHP.
What Is a PHP Class?
First we need to understand what PHP classes are. A class is a template which represents a real-world entity, and it defines properties and methods of the entity. In this section, we’ll discuss the basic anatomy of a typical PHP class.
The best way to understand new concepts is with an example. So let’s have a look at the Employee class in the following snippet, which represents the employee entity.