Constructor inheritance in PHP - Mini Project: Build & Apply

Constructor inheritance

📖 Scenario: Imagine you are creating a simple system to manage different types of vehicles. Each vehicle has a brand and a model. Cars are a special type of vehicle that also have a number of doors.

🎯 Goal: You will create a base class Vehicle with a constructor to set brand and model. Then create a subclass Car that inherits from Vehicle and adds the number of doors. You will use constructor inheritance to reuse the base class constructor.

📋 What You'll Learn

Create a class Vehicle with a constructor that takes $brand and $model and sets them as properties.

Create a subclass Car that extends Vehicle.

In Car, create a constructor that takes $brand, $model, and $doors.

Use parent::__construct($brand, $model) inside Car constructor to call the base constructor.

Add a property $doors in Car and set it in the constructor.

Create an instance of Car with brand 'Toyota', model 'Corolla', and 4 doors.

Print the brand, model, and doors of the car.

💡 Why This Matters

🌍 Real World

Constructor inheritance is used in many real-world PHP applications to reuse code and organize related classes efficiently, such as in vehicle management systems, user roles, or product categories.

💼 Career

Understanding constructor inheritance is important for PHP developers working on object-oriented projects, frameworks, or any codebase that uses class hierarchies.

1

Create the base class Vehicle

Create a class called Vehicle with a constructor that takes parameters $brand and $model. Inside the constructor, set these parameters to properties $this->brand and $this->model.

PHP

<?php

// Create class Vehicle with constructor
// Your code here

Need a hint?

Use class Vehicle { ... } and inside it define public function __construct($brand, $model).

2

Create subclass Car with constructor

Create a class called Car that extends Vehicle. Add a constructor that takes $brand, $model, and $doors. Inside the constructor, call parent::__construct($brand, $model) to reuse the base constructor. Also set $this->doors to $doors.

PHP

brand = $brand;
        $this->model = $model;
    }
}

// Create class Car that extends Vehicle with constructor
// Your code here

Need a hint?

Use class Car extends Vehicle and inside the constructor call parent::__construct($brand, $model).

3

Create an instance of Car

Create a variable called $myCar and set it to a new Car object with brand 'Toyota', model 'Corolla', and 4 doors.

PHP

brand = $brand;
        $this->model = $model;
    }
}

class Car extends Vehicle {
    public $doors;

    public function __construct($brand, $model, $doors) {
        parent::__construct($brand, $model);
        $this->doors = $doors;
    }
}

// Create an instance of Car
// Your code here

Need a hint?

Use $myCar = new Car('Toyota', 'Corolla', 4); to create the object.

4

Print the car details

Print the brand, model, and number of doors of $myCar using echo. Format the output exactly as: Brand: Toyota, Model: Corolla, Doors: 4

PHP

brand = $brand;
        $this->model = $model;
    }
}

class Car extends Vehicle {
    public $doors;

    public function __construct($brand, $model, $doors) {
        parent::__construct($brand, $model);
        $this->doors = $doors;
    }
}

$myCar = new Car('Toyota', 'Corolla', 4);

// Print the car details
// Your code here

Need a hint?

Use echo "Brand: {$myCar->brand}, Model: {$myCar->model}, Doors: {$myCar->doors}"; to print the details.