dependency injection with interface

dependencyinjectionwithinterface.php

<?php

declare(strict_types=1);

namespace DemoPhpframework;

/**
 * Dependency Injection from a bible Base Creation Example
 *
 * First what is Dependency Injection:
 * Dependency injection says that instead of a class accessing other dependencies (say class, or objects of a class, etc) instead that dependency ( class, object, etc) is supplied or provided to it. In otherwords, a classdoesn't need to reachout but it is supplied with what ever neccesary class, object, etc it will be needing.
 *
 *
 * For further reading : https://php-di.org/doc/understanding-di.html
 *
 */

//another instance. Lets implement interfaces with dependecny injection

//interface
interface CreationInterface
{
    public function spokenWord();
}

// Day one of creation, what did God say ? What is the word God spoke ?
class DayOne implements CreationInterface
{
    public function spokenWord()
    {
        echo " Let there be Light !!!!";
    }
}

// Day five of creation, what did God say ? What is the word God spoke ?
class DayFive implements CreationInterface
{
    public function spokenWord()
    {
        echo " Lets create man in our own image and in our likeness";
    }
}

// dependency injection here:
class beginCreation
{
    private $whatGodSaid;

    public function __construct(CreationInterface $whatGodSaid)
    {
        $this->whatGodSaid = $whatGodSaid;
    }


    public function execute()
    {
        return $this->whatGodSaid->spokenWord();
    }
}

$dayOne = new dayFive(); // change/instantiate dayOne class
$beginCreation = new beginCreation($dayOne);

echo $beginCreation->execute();