php oop don't know where/how to use it

Question

Again here....

I'm trying to learn PHP OOP (like in the last post), but as much as I read, I can not find the use of classes, methods and properties very well. So at the moment I don't find any sense to all of this. So I've thought it would be good to try to do an easy script using OOP to find why OOP is useful.

Would be the right exercise to do an script to calculate areas? Like... you choose circle, square or rectangle, then you add the height, width or ratio and it gives to the area in cm2. Would it be a script to practise OOP?

I'm so confused!!!! And internet is confusing me even more! If this is not a good idea... could anyone tell me a script where I can see I need to create properties.... initiate classes.... or mainly, can anyone suggest what script I could do being easy to follow and do step by step?

I've been practising with

class Cars {
    public $color
    public $brand
    public $doors
} 

To see how __construct, destruct and $this work, but I don't know what to do with it.... I mean.... in what case could I need to do this?

Thank you!

Answer 1

OOP in PHP is a really easy and convenient way to write your application in PHP. You need to learn about class, objects, instance, interface, trait, abstract class and methods, static methods, magic methods etc.

Classes are bunch of methods and properties. Methods are almost like functions. properties are like variables.

There are some way to access properties and methods. In a class you can set public,private and protected methods and properties. You can access public methods and properties any where in your application. You can access private methods and properties only inside that class it resides and You can access protected methods and properties inside base class and child class.

In short learning OOP style is really fun. and it is so easy and efficient way to write application. php.net is really a great source to learn OOP style. This is the link PHP OOP

And there are also a lot of books on internet on PHP OOP style. Hope this will help.

Answer 2

One of the "best" examples when OOP is way easier than procedural is a nifty structure like a tree.

Trees are quite common structure (like navigation menus). To create a tree with infinite depth the procedural way is "hard" while using OOP it's simple.

Secondly you can easily hide certain functionality to the scope of an object. (i.e. public vs private vs protected).

Using cars / animals etc etc is usually useful when interfaces / subclasses come into play.

A too simple Tree as an example

class Tree {
    private $parent = null;
    private $nodes = array();

    private $data;

    function __construct($data) {
        $this->setData($data);
    }

    function setData($data) {
        $this->data = $data;
    }

    function getData() {
        return $this->data;
    }

    function getNode($index) {
        return (isset($this->nodes[$index]) ? $this->nodes[$index] : null);
    }

    function addNode(Tree $node) {
        $this->nodes[] = $node;
    }

    function getParent() {
        return $this->parent;
    }

    function isRoot() {
        return ($this->parent === null);
    }

    function getRoot() {
        return ($this->isRoot() ? $this : $this->getParent()->getRoot());
    }
}