Overriding Parent Methods in OOP in PHP

A child class can override a parent method by creating a method with the same name. Let's look at an example. Suppose we have the following parent class:

php<?php
  class User {
    private $name;
    
    public function setName($name) {
      $this->name = $name;
    }
    public function getName() {
      return $this->name;
    }
  }
?>

Let's create a method with the same name in the child class:

php<?php
  class Student extends User {
    public function setName($name) {
      
    }
  }
?>

Typically, overriding parent methods is necessary to change or extend the behavior of that method. In our case, let's add a check for the name length:

php<?php
  class Student extends User {
    public function setName($name) {
      if (strlen($name) > 0) {
        $this->name = $name;
      } else {
        echo 'student name error';
      }
    }
  }
?>

Let's make sure that it is the overridden method that is called. First, let's create an object of the child class:

php<?php
  $student = new Student;
?>

Now let's call our method, passing a valid value to it:

php<?php
  $student->setName('john');
?>

And now let's call the method, passing an invalid value to it. As a result, we will see the thrown exception:

php<?php
  $student->setName(''); // error
?>