What is PHP Interface? What Three Can Be Used For? How Much Should You Use?

23 June 2023 229 Reading time: 2 minute

The "interface" in PHP is an object-oriented programming (OOP) construct. An interface defines methods and properties with which a class will implement a certain behavior. A class can implement more than one interface, thus providing multiple inheritance.

The purpose of an interface is to enable one or more classes to implement a certain behavior. Interfaces are used to provide abstraction and compatibility in application design. Interfaces define how a class should behave, but are not concerned with how that behavior is performed. Thus, an interface can contain signatures of methods and constants used to define common properties between classes.

We use the keyword "interface" to define an interface in PHP. Interfaces allow classes to implement the interface with the keyword "implements". When a class implements an interface, it must implement all the methods defined in the interface. To use a property defined in the interface, the class must define that property.

PHP interface example:

interface Adding {
    public function add($data);
}

class Database implements Adding {
    public function add($data) {
        // add data to database
    }
}

class File implements Adding {
    public function add($data) {
        // Data add to file
    }
}

In the above example, we defined an interface named "Addable" and it has a method named "add". The "Database" and "File" classes are classes that implement the "Plugable" interface and must implement the "add" method. In this way, both classes can be used to add data in a different way.

Interfaces make the code more flexible because a class can implement more than one interface and that way it can be used for different purposes. Also, interfaces create a contract between classes and provide better code organization and maintenance.

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