Simple Factory
Real world example
Consider, you are building a house and you need doors. It would be a mess if every time you need a door, you put on your carpenter clothes and start making a door in your house. Instead you get it made from a factory.
In plain words
Simple factory simply generates an instance for client without exposing any instantiation logic to the client
Wikipedia says
In object-oriented programming (OOP), a factory is an object for creating other objects – formally a factory is a function or method that returns objects of a varying prototype or class from some method call, which is assumed to be "new".
Programmatic Example
First of all we have a door interface and the implementation
interface Door
{
public function getWidth(): float;
public function getHeight(): float;
}
class WoodenDoor implements Door
{
protected $width;
protected $height;
public function __construct(float $width, float $height)
{
$this->width = $width;
$this->height = $height;
}
public function getWidth(): float
{
return $this->width;
}
public function getHeight(): float
{
return $this->height;
}
}
Then we have our door factory that makes the door and returns it
class DoorFactory
{
public static function makeDoor($width, $height): Door
{
return new WoodenDoor($width, $height);
}
}
And then it can be used as
$door = DoorFactory::makeDoor(100, 200);
echo 'Width: ' . $door->getWidth();
echo 'Height: ' . $door->getHeight();
When to Use?
When creating an object is not just a few assignments and involves some logic, it makes sense to put it in a dedicated factory instead of repeating the same code everywhere.