What are the potential issues with including PHP files within a method in a controller/template system?

Including PHP files within a method in a controller/template system can lead to code duplication, reduced readability, and potential security vulnerabilities. To solve this, it is recommended to use a template engine like Twig or Blade to separate the presentation logic from the business logic in your application.

// Example using Twig template engine
$loader = new \Twig\Loader\FilesystemLoader('/path/to/templates');
$twig = new \Twig\Environment($loader);

$template = $twig->load('index.html');
echo $template->render(['data' => $data]);