Question

I am new to php oop, I have a some idea re Classes but I still don’t get around how to use its properties and methods in a created Object. I need to understand if the code reported below is correct, and if not what I do wrong.

I am assuming that I have a Class that can do anything for me. Let’s call it Class myClass {….}

Now I create an object from it and try to work with its methods and properties like this:-

$myObject = new myClass;

$myObject->checkSpeedLight(); // method for checking the speed

if($this->lightSpeed > 10000) echo (“slow down!”); // property defined with a value of 10000

if($this->lightSpeed =< 10000) echo (“Speed up!);

$myObject->keepLightingUp();

$myObject->sleep();

echo ("ligth up");

It has no sense I know, it is just an example. What I need to understand is if the way is written is correct; Any help appreciated.

Answer 1

$this is out of context, it can only be used from within the class definition (inside of internal methods etc).

Outside of the function, we use $myObject->lightspeed;

Also, I’m assuming that you are setting the lightspeed property with the checkLightSpeed() method.

EDIT!
Additionally, it’s considered good practice to have a getter and setter methods. The point is to not access your properties directly, but through an abstraction layer method.

class MyClass {
    private $property = "Hello World!";

    public function getProperty() {
        return $this->property;
    }
}

$obj = new MyClass();
$obj->getProperty();

This way you have more control over what, how and when you view your property (for instance, you can require a database connection in order to view it, or restrict access).

Also note that the property itself is declared private, so direct access from outside the class’s guts is restricted.

---

For instance, this is my SpeedOfLight class made in PHP:

<?php

    /**
     * @class                  SpeedOfLight
     *
     * @property $speedOfLight private
     *
     */
    class SpeedOfLight {

        private $speedOfLight;

        public function checkSpeedOfLight() {
            $this->speedOfLight = 300000000;
        }

        public function getSpeedOfLight() {
            return $this->speedOfLight;
        }

    }

    #Begin testing!
    $obj = new SpeedOfLight();
    $obj->checkSpeedOfLight();

    if ($obj->getSpeedOfLight() <= 100000000) {
        echo "Speed up!";
    }
    elseif ($obj->getSpeedOfLight() >= 350000000) {
        echo "Slow down!";
    }
    else {
        echo "Just right!";
    }

(I didn’t know what keepLightSpeed() or sleep() were so I omitted them, but this is the key part).

---

Other than that, you’re good.