Why design patterns matter in PHP - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a simple class in PHP.

PHP

<?php
class Car {
    public function [1]() {
        echo "Car started";
    }
}
?>

Drag options to blanks, or click blank then click option'

Arun

Bstart

Cdrive

Dmove

Attempts:

3 left

💡 Hint

Common Mistakes

Using method names that do not describe starting, like 'run' or 'move'.

The method name start is used to indicate starting the car.

2fill in blank

medium

Complete the code to implement a singleton pattern method.

PHP

<?php
class Logger {
    private static $instance = null;

    public static function [1]() {
        if (self::$instance === null) {
            self::$instance = new Logger();
        }
        return self::$instance;
    }
}
?>

Drag options to blanks, or click blank then click option'

AnewInstance

BgetLogger

CgetInstance

Dcreate

Attempts:

3 left

💡 Hint

Common Mistakes

Using method names like 'create' or 'newInstance' which do not follow singleton conventions.

The method getInstance is the standard name to access the singleton instance.

3fill in blank

hard

Fix the error in the code to correctly implement dependency injection.

PHP

<?php
class Database {
    private $connection;

    public function __construct([1] $connection) {
        $this->connection = $connection;
    }
}
?>

Drag options to blanks, or click blank then click option'

APDO

Bmysqli

CConnection

DDatabaseConnection

Attempts:

3 left

💡 Hint

Common Mistakes

Using undefined or incorrect class names like 'Connection' or 'DatabaseConnection'.

The PDO class is commonly used for database connections in PHP and fits here.

4fill in blank

hard

Fill both blanks to complete the factory method pattern.

PHP

<?php
interface [1] {
    public function createProduct();
}

class [2] implements ProductFactory {
    public function createProduct() {
        return new Product();
    }
}
?>

Drag options to blanks, or click blank then click option'

AProductFactory

BFactory

CProductCreator

DCreator

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same name for interface and class, causing a PHP name conflict.

The interface ProductFactory defines the factory method, and the class ProductCreator implements it to follow the factory method pattern.

5fill in blank

hard

Fill all three blanks to complete the observer pattern example.

PHP

<?php
interface [1] {
    public function update([2] $subject);
}

class [3] implements Observer {
    public function update([2] $subject) {
        echo "Subject state changed.";
    }
}
?>

Drag options to blanks, or click blank then click option'

AObserver

BSubject

CConcreteObserver

DListener

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong interface or class names that do not match the observer pattern.

The interface is Observer, the parameter type is Subject, and the class implementing the observer is ConcreteObserver.