Adapter pattern using real world example in PHP

Photo by Mika Baumeister on Unsplash

I am picking DSLR camera lenses as a real world example:

Photo by Conor Luddy on Unsplash

what is adapter pattern ?

The Adapter Pattern is a design pattern that allows two incompatible interfaces to work together by creating an adapter that maps the methods of one interface to the other

NOW

There are 11 Types Of Camera Lenses (For DSLR) we will be choosing only two to understand the pattern

1. Sony Lenses
2. Nikon Lenses

interface Lens
{
    public function zoomIn();
    public function zoomOut();
    public function focus();
}

class NikonLens implements Lens
{
    public function zoomIn()
    {
        // code
    }

    public function zoomOut()
    {
        // code
    }

    public function focus()
    {
        // code
    }
}

interface SonyLensInterface 
{
    public function zoomIn();
    public function zoomOut();
    public function autofocus();
}

class SonyLens implements SonyLensInterface
{
   public function zoomIn()
    {
        // code 
    }

    public function zoomOut()
    {
        // code
    }

    public function autofocus()
    {
        // code
    }
}

class SonyLensAdapter implements Lens
{
    protected $sonyLens;

    public function __construct(SonyLensInterface $sonyLens)
    {
        $this->sonyLens = $sonyLens;
    }

    public function zoomIn()
    {
        $this->sonyLens->zoomIn();
    }

    public function zoomOut()
    {
        $this->sonyLens->zoomOut();
    }

    public function focus()
    {
        $this->sonyLens->autofocus();
    }
}

Let me explain it !

In the above code say we want to add support for a new type of lens, SonyLens, that also implements the Lens interface, but has a different implementation of the methods. To use the SonyLens with our Camera class, we can create an adapter class, SonyLensAdapter, that adapts the SonyLens to our Lens interface.

The SonyLensAdapter class implements the Lens interface, and wraps a SonyLens object. The zoomIn(), zoomOut(), and focus() methods of the adapter delegate to the corresponding methods of the wrapped SonyLens object.

But for focus() SonyLens can autofocus()

$sonyLens = new SonyLens();
$sonyLensAdapter = new SonyLensAdapter($sonyLens);
$sonyLensAdapter->focus();

Simply that’s it.

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