Classes are a unit of code organization in PHP.
Code represents the behavior of an item or the behavior of a process can be grouped together as a class.
Functions that are assigned to a class are called methods
by convention.
<?php
class Door
{
function lock()
{
// ...
}
function unlock()
{
// ...
}
}
Classes are instantiated with the new
keyword, this allocates memory for the class instance and calls the classes constructor method.
Instantiated classes may be assigned to a variable.
To invoke the methods of a class instance, we can use the ->
access operator.
<?php
$a_door = new Door();
$a_door->lock();
$a_door->unlock();
An instantiated class may reference its own instance using the special $this
variable.
Classes may also have properties, these act as variables that are tied to the instance of the class object.
These properties may be referenced internally or externally.
<?php
class Car
{
public $color;
function __construct($color)
{
$this->color = $color;
}
function getColor()
{
return $this->color;
}
}
$a_car = new Car("red");
$a_car->color; // => "red" by accessing the property
$a_car->getColor(); // => "red" by invoking the instance method