Create and instantiate a class in PHP

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A great way to structure your code, once it gets more complex, is to use PHP classes. Classes allow you to organize and colocate multiple functions of business logic together into a unified entity.

Create a new file at classes/Author.php and add a new Author class. We will do this with the class keyword, followed by the name of the class we’d like to create, Author.

<?php declare(strict_types=1);

class Author
{

}

Now we will include that class with a require statement. Let’s require it in the functions.php file:

<?php declare(strict_types=1);

require('classes/Author.php');

function getPosts(): array
{
    return [
        [
            'title' => 'How to learn PHP',
            'content' => 'This is how you learn PHP.',
        ],
        [
            'title' => 'How to learn MySQL',
            'content' => 'This is how you learn MySQL.',
        ],
        [
            'title' => 'How to learn Nginx',
            'content' => 'This is how you learn Nginx.',
        ],
    ];
}

function getPostText(int $numPosts): string
{
    return $numPosts === 1 ? 'post' : 'posts';
}

PHP object instantiation happens with a special PHP keyword, new. When we follow new with the class name we’d like to create, followed by parenthesis, when PHP parses this code, it will create a new object that is an instance of this class.

<?php declare(strict_types=1);

require('classes/Author.php');

function getPosts(): array
{
    $author = new Author();

    return [
        [
            'title' => 'How to learn PHP',
            'content' => 'This is how you learn PHP.',
        ],
        [
            'title' => 'How to learn MySQL',
            'content' => 'This is how you learn MySQL.',
        ],
        [
            'title' => 'How to learn Nginx',
            'content' => 'This is how you learn Nginx.',
        ],
    ];
}

function getPostText(int $numPosts): string
{
    return $numPosts === 1 ? 'post' : 'posts';
}

At this moment, this code is just creating a new instance of this object, and assigning it to the $author variable. This variable now holds a reference to this newly created object.