Example of Decorator Pattern, using php8 constructor property promotion

Design patterns are cool but hard to memorize. I think that emoji and new php8 constructor property promotion help simplify the scheme. Take a look.

<?php

interface Product { public function cost(): int; }

class 📱 implements Product
{
    public function cost(): int { return 699; }
}

class 🎧 implements Product
{
    public function __construct(public Product $product) {}
    public function cost(): int { return $this->product->cost() + 549; }
}

class 🔌 implements Product
{
    public function __construct(public Product $product) {}
    public function cost(): int { return $this->product->cost() + 19; }
}

echo 'only $' . (new 🔌(new 🎧(new 📱)))->cost(); // only $1267
echo 'only $' . (new 🎧(new 🔌(new 📱)))->cost(); // only $1267