Отделить абстракцию от её реализации так, что они могут изменяться независимо друг от друга.

Вы можете найти этот код на GitHub

Formatter.php

<?php
 
declare(strict_types=1);
 
namespace DesignPatterns\Structural\Bridge;
 
interface Formatter
{
    public function format(string $text): string;
}

PlainTextFormatter.php

<?php
 
declare(strict_types=1);
 
namespace DesignPatterns\Structural\Bridge;
 
class PlainTextFormatter implements Formatter
{
    public function format(string $text): string
    {
        return $text;
    }
}

HtmlFormatter.php

<?php
 
declare(strict_types=1);
 
namespace DesignPatterns\Structural\Bridge;
 
class HtmlFormatter implements Formatter
{
    public function format(string $text): string
    {
        return sprintf('<p>%s</p>', $text);
    }
}

Service.php

<?php
 
declare(strict_types=1);
 
namespace DesignPatterns\Structural\Bridge;
 
abstract class Service
{
    public function __construct(protected Formatter $implementation)
    {
    }
 
    public function setImplementation(Formatter $printer)
    {
        $this->implementation = $printer;
    }
 
    abstract public function get(): string;
}

HelloWorldService.php

<?php
 
declare(strict_types=1);
 
namespace DesignPatterns\Structural\Bridge;
 
class HelloWorldService extends Service
{
    public function get(): string
    {
        return $this->implementation->format('Hello World');
    }
}

PingService.php

<?php
 
declare(strict_types=1);
 
namespace DesignPatterns\Structural\Bridge;
 
class PingService extends Service
{
    public function get(): string
    {
        return $this->implementation->format('pong');
    }
}

Tests/BridgeTest.php

<?php
 
declare(strict_types=1);
 
namespace DesignPatterns\Structural\Bridge\Tests;
 
use DesignPatterns\Structural\Bridge\HelloWorldService;
use DesignPatterns\Structural\Bridge\HtmlFormatter;
use DesignPatterns\Structural\Bridge\PlainTextFormatter;
use PHPUnit\Framework\TestCase;
 
class BridgeTest extends TestCase
{
    public function testCanPrintUsingThePlainTextFormatter()
    {
        $service = new HelloWorldService(new PlainTextFormatter());
 
        $this->assertSame('Hello World', $service->get());
    }
 
    public function testCanPrintUsingTheHtmlFormatter()
    {
        $service = new HelloWorldService(new HtmlFormatter());
 
        $this->assertSame('<p>Hello World</p>', $service->get());
    }
}