A simple PHP template class.

simple-template-class.php

<?php

/**
 * Class Template - a very simple PHP class for rendering PHP templates
 */
class Template {

	/**
	 * Location of expected template
	 *
	 * @var string
	 */
	public $folder;

	/**
	 * Template constructor.
	 *
	 * @param $folder
	 */
	function __construct( $folder = null ){
		if ( $folder ) {
			$this->set_folder( $folder );
		}
	}

	/**
	 * Simple method for updating the base folder where templates are located.
	 *
	 * @param $folder
	 */
	function set_folder( $folder ){
		// normalize the internal folder value by removing any final slashes
		$this->folder = rtrim( $folder, '/' );
	}

	/**
	 * Find and attempt to render a template with variables
	 *
	 * @param $suggestions
	 * @param $variables
	 *
	 * @return string
	 */
	function render( $suggestions, $variables = array() ){
		$template = $this->find_template( $suggestions );
		$output = '';

		if ( $template ){
			$output = $this->render_template( $template, $variables );
		}

		return $output;
	}

	/**
	 * Look for the first template suggestion
	 *
	 * @param $suggestions
	 *
	 * @return bool|string
	 */
	function find_template( $suggestions ){
		if ( !is_array( $suggestions ) ) {
			$suggestions = array( $suggestions );
		}

		$suggestions = array_reverse( $suggestions );

		$found = false;

		foreach( $suggestions as $suggestion ){
			$file = "{$this->folder}/{$suggestion}.php";

			if ( file_exists( $file ) ){
				$found = $file;
				break;
			}
		}

		return $found;
	}

	/**
	 * Execute the template by extracting the variables into scope, and including
	 * the template file.
	 *
	 * @internal param $template
	 * @internal param $variables
	 *
	 * @return string
	 */
	function render_template( /*$template, $variables*/ ){
		ob_start();

		foreach ( func_get_args()[1] as $key => $value) {
			${$key} = $value;
		}

		include func_get_args()[0];

		return ob_get_clean();
	}
}

user-profile-example-template-suggestions-usage.php

<?php

$suggestions = array( 'user-profile-example-template' );

// provide more-specific template suggestions for logged in users
if ( user_is_logged_in() ) {
  
  // provide a generic template suggestion for all users of a given type
  if ( user_is_of_special_type() ) {
    $suggestions[] = 'user-profile-' . $user->type;
  }

  // provide the most-specific template suggestion possible for this user.
  $suggestions[] = 'user-profile-' . $user->id;
}

$tpl = new Template( 'path/to/templates/folder' );
$tpl->render( $suggestions, array(
  'user_name' => $user->name,
  'user_bio' => $user->bio
) );

user-profile-example-template.php

<div class="user-profile">
	<h3 class="title"><?php echo $user_name; ?></h3>
	<div class="content"><?php echo $user_bio; ?></div>
</div>

Hm what's up with this:
https://gist.github.com/daggerhart/730e8a9d79f37a461d985b158d0108ab#file-simple-template-class-php-L33
Also, should not this be mandatory:
https://gist.github.com/daggerhart/730e8a9d79f37a461d985b158d0108ab#file-simple-template-class-php-L22

@Cyclonecode, good catch on the doulbe $this->folder = $this->folder = ..., that was a typo I had obviously missed for years.

The $folder constructor parameter is optional. You shouldn't have to provide a folder path during construction of the object.

Ah, but if you don't supply a folder path the following will never work right:
https://gist.github.com/daggerhart/730e8a9d79f37a461d985b158d0108ab#file-simple-template-class-php-L72

@Cyclonecode, that's true. I made it optional in the constructor, but when not provided a user would need to make use of the set_folder() method themselves. What would you recommend as an improvement to the class? I'm open to any ideas that make it more reliable and easy to use.

First of all I think I would set visibility for the different methods,. For instance I guess the render_template(), find_template() and so on really should not be used by a user directly? If this is the case I really think they should be declared as private or protected. Of course the folder property also should be set to private or protected in this case. After that I think changing the render() method to something like this might be a good idea:

	public function render( $suggestions, $variables = array() ){
                // Make sure we have a folder path, perhaps we should also check so the folder is readable?
                if ( !$this->folder || !is_dir($this->folder)) {
			throw new Exception('You need to set the base folder for all templates using set_folder().');
                }
		$template = $this->find_template( $suggestions );
		$output = '';
		if ( $template ){
			$output = $this->render_template( $template, $variables );
		}
		return $output;
	}