wp-learn-php-compatibility.php

<?php 
/**
 * Plugin Name: WP Learn Compatibility
 * Description: Learn to test a plugin for PHP Version Compatibility 
 * Version: 1.0.1
 */

/**
 * Posts fetcher class
 */
class post_fetcher {

	protected $posts;

	public function post_fetcher() {
		$this->posts     = get_posts();
	}

	public function fetch_posts() {
		$post_html = '<div class="post">';
		foreach ( $this->posts as $post ) {
			if ( property_exists( $post, 'post_title' ) ) {
				$post_html .= sprintf(
					'<h4><a href="%s">%s</a></h4>',
					get_permalink( $post->ID ),
					$post->post_title
				);
			}
		}
		$post_html .= '</div>';
		return $post_html;
	}
}

/**
 * Shortcode to render posts
 * Uses the post_fetcher class
 */
add_shortcode( 'wp_learn_php_compatibility', 'wp_learn_php_compatibility_shortcode_render' );
function wp_learn_php_compatibility_shortcode_render() {
	$post_fetcher = new post_fetcher();
	$post_html = $post_fetcher->fetch_posts();
	return $post_html;
}