Abstract Classes in PHP - PHP OOPs Abstract Class

PHP - Abstract Classes

• Abstract classes are classes that contain one or more abstract methods.
• An abstract method is a method that is declared, but not implemented in the code.
• Subclasses of the abstract class must implement all of the abstract methods in order to be instantiated.
• Abstract classes cannot be instantiated, and they are often used as a base class for other classes to extend from.

Syntax

<?php
abstract class BaseClass {
  abstract public function someMethod1();
  abstract public function someMethod2($name, $color);
  abstract public function someMethod3() : string;
}
?>

Sample Code

<?php
// Base class
abstract class Car {
  public $name;
  public function __construct($name) {
    $this->name = $name;
  }
  abstract public function intro() : string;
}

// Derived classes
class Audi extends Car {
  public function intro() : string {
    return "Choose German quality! I'm an $this->name!";
  }
}

class Volvo extends Car {
  public function intro() : string {
    return "Proud to be Swedish! I'm a $this->name!";
  }
}

class Citroen extends Car {
  public function intro() : string {
    return "French extravagance! I'm a $this->name!";
  }
}
// Create objects from the derived classes
$audi = new audi("Audi");
echo $audi->intro();
echo "<br>";

$volvo = new volvo("Volvo");
echo $volvo->intro();
echo "<br>";

$citroen = new citroen("Citroen");
echo $citroen->intro();
?>

Output

Choose Indian quality! I'm an Tata!
Proud to be a Korean! I'm a Kia!
British extravagance! I'm a MG!

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