Type hinting with parent classes in PHP - Mini Project: Build & Apply

Type hinting with parent classes

📖 Scenario: You are building a simple system to manage different types of vehicles. Each vehicle has a method to display its type. You want to use type hinting with a parent class to ensure your functions accept any vehicle type.

🎯 Goal: Create a parent class Vehicle and two child classes Car and Bike. Then write a function that accepts a Vehicle type and calls its method to display the vehicle type.

📋 What You'll Learn

Create a parent class called Vehicle with a method getType().

Create two child classes Car and Bike that extend Vehicle and override getType().

Write a function printVehicleType that accepts a parameter type hinted as Vehicle.

Call getType() inside printVehicleType and print the result.

💡 Why This Matters

🌍 Real World

Type hinting with parent classes helps write flexible code that works with many related objects, like different vehicle types in a transport app.

💼 Career

Understanding inheritance and type hinting is essential for writing clean, maintainable PHP code in many software development jobs.

1

Create the parent class Vehicle

Create a class called Vehicle with a public method getType() that returns the string 'Generic Vehicle'.

PHP

<?php

// Create class Vehicle with method getType()
// Your code here

Need a hint?

Use class Vehicle {} and inside it define public function getType(): string that returns 'Generic Vehicle'.

2

Create child classes Car and Bike

Create two classes called Car and Bike that extend Vehicle. Override the getType() method in each to return 'Car' and 'Bike' respectively.

PHP

<?php

class Vehicle {
    public function getType(): string {
        return 'Generic Vehicle';
    }
}

// Create class Car extending Vehicle
// Create class Bike extending Vehicle
// Your code here

Need a hint?

Use class Car extends Vehicle and override getType() to return 'Car'. Do the same for Bike returning 'Bike'.

3

Write function with type hinting for Vehicle

Write a function called printVehicleType that accepts one parameter $vehicle type hinted as Vehicle. Inside the function, call $vehicle->getType() and print the returned string.

PHP

<?php

class Vehicle {
    public function getType(): string {
        return 'Generic Vehicle';
    }
}

class Car extends Vehicle {
    public function getType(): string {
        return 'Car';
    }
}

class Bike extends Vehicle {
    public function getType(): string {
        return 'Bike';
    }
}

// Write function printVehicleType with parameter type hinted as Vehicle
// Your code here

Need a hint?

Define function printVehicleType(Vehicle $vehicle): void and inside use echo $vehicle->getType() to print the type.

4

Call function with Car and Bike objects and print output

Create an object $car of class Car and an object $bike of class Bike. Call printVehicleType with $car and then with $bike to print their types.

PHP

getType() . "\n";
}

// Create $car as Car object
// Create $bike as Bike object
// Call printVehicleType with $car and $bike
// Your code here

Need a hint?

Create objects with new Car() and new Bike(). Then call printVehicleType($car) and printVehicleType($bike).