PHP OOP · Episode 09

OOP: The Constructor (__construct)

Set an object’s data the moment it’s created

ep9_oop_constructors.php

<?php
class Car {

    public $color;
    public $model;
    public $brand;

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

    function getCarMake(){
        return "The car brand is $this->brand and the model is $this->model and the color is $this->color";
    }

}

$carOne = new Car("white" , "safari" , "Tata");
$carTwo = new Car("black" , "scorpio" , "Mahindra");

Output

Output for this tutorial goes here.

The car brand is Tata and the model is safari and the color is white The car brand is Mahindra and the model is scorpio and the color is black

The Problem

In the last episode we created an object and then set each property one line at a time ($car->color = …). That’s repetitive, and it’s easy to forget a value — leaving an object half‑built.

The Constructor

__construct() is a special method that PHP runs automatically the moment you create an object with new. Put your setup logic here and every object starts life fully populated.

Whatever you pass to new Car(…) is handed straight to the constructor’s parameters, and $this->color = $color stores it on the object.

Why it’s better

One clear line creates a ready‑to‑use object: new Car("white", "Safari", "Tata"). Fewer lines, no forgotten properties, and the class controls how it’s built.

Example Output

$carOne->getCarMake() → The car brand is Tata and the model is Safari and the color is white

$carTwo->getCarMake() → The car brand is Mahindra and the model is Scorpio and the color is black

Key takeaway: __construct() runs automatically on new and sets up the object in one step — cleaner and safer than assigning properties from outside.

Pro tips: give parameters defaults (e.g. __construct($color = "black")) to make them optional. And in PHP 8+, constructor property promotion lets you declare and assign in one go: public function __construct(public $color, public $model) {} — no separate property lines needed.

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