Decorator Pattern Example #php #design-patterns #decorator-pattern

decorator-pattern.php

<?php

interface IGreeting
{
    public function greeting();
}

abstract class GreetingDecorator implements IGreeting
{
    protected $greeter;

    public function __construct(IGreeting $greeter)
    {
        $this->greeter = $greeter;
    }

    public function greeting()
    {
        if ($this->greeter instanceof IGreeting)
        {
            $this->greeter->greeting();
        }
    }
}

class HelloGreeting implements IGreeting
{
    public function greeting()
    {
        echo "Hello, \n";
    }
}

class ThanksgivingGreeting extends GreetingDecorator
{
    public function greeting()
    {
        parent::greeting();
        echo "Happy Thanksgiving!\n";
    }
}

class ChristmasGreeting extends GreetingDecorator
{
    public function greeting()
    {
        parent::greeting();
        echo "Merry Christmas!\n";
    }
}

$greeter = new ThanksgivingGreeting(new HelloGreeting);
$greeter->greeting();