Example of the Abstract Factory Design Pattern

ChairFactory.php

<?php

class ChairFactory
{
    public function createChair(bool $cheap, bool $fancy): ChairInterface
    {
        if ($cheap && $fancy) {
            return new ModernChair();
        } elseif ($fancy) {
            return new VictorianRockingChair();
        } elseif ($cheap) {
            return new SimpleChair();
        } else {
            throw new Exception('No chair matches that criteria');
        }
    }
}

interface ChairInterface
{
    public function getPrice();
}

class SimpleChair implements ChairInterface
{
    public function getPrice()
    {
        return 79.99;
    }
}

class ModernChair implements ChairInterface
{
    public function getPrice()
    {
        return 149.99;
    }

    public function swivel()
    {
        // See the world around you
    }
}

class VictorianRockingChair implements ChairInterface
{
    public function getPrice()
    {
        return 199.99;
    }

    public function rockBackAndForth()
    {
        // rock out
    }
}