WordPress plugin to show the current used template file name in the admin bar.

dna-tpl-to-admin-bar.php

<?php

/**
 * Plugin Name: dna Template Name to Admin Bar
 * Plugin URI:  https://gist.github.com/4690246
 * Description: Shows the current used theme template file in the admin bar. (Requires PHP 5.3)
 * Author:      David Naber
 * Author URI:  http://dnaber.de/
 * Version:     2013.11.09
 * License:     MIT
 * License URI: http://opensource.org/licenses/mit-license.php
 */
namespace dna\tpl_to_admin_bar;

if ( ! function_exists( 'add_filter' ) )
	return;

add_action( 'plugins_loaded', array( Plugin::get_instance(), 'init_plugin' ) );

class Plugin {

	/**
	 * the plugin instance
	 *
	 * @var Plugin
	 */
	private static $instance = NULL;

	/**
	 * the template full path
	 *
	 * @var string
	 */
	protected $template;

	/**
	 * the template basename
	 *
	 * @since 2013.11.09
	 * @var string
	 */
	protected $template_basename;

	/**
	 * get the plugin instance
	 *
	 * @return Plugin
	 */
	public static function get_instance() {

		if ( NULL === self::$instance )
			self::$instance = new self;

		return self::$instance;
	}

	/**
	 * hook in
	 *
	 * @wp-hook plugins_loaded
	 */
	public function init_plugin() {

		if ( is_admin() )
			return;

		add_filter( 'template_include', array( $this, 'pick_template' ), 999 );
		add_action( 'wp_before_admin_bar_render', array( $this, 'admin_bar' ) );

	}

	/**
	 * fishing the template name out
	 *
	 * @wp-hook template_include
	 * @param string $template
	 * @return string
	 */
	public function pick_template( $template ) {

		$this->template = $template;
		$this->template_basename = basename( $template );

		return $template;
	}

	/**
	 * add a item to the admin bar
	 *
	 * @wp-hook wp_before_admin_bar_render
	 * @global $wp_admin_bar;
	 * @return
	 */
	public function admin_bar() {

		$GLOBALS[ 'wp_admin_bar' ]->add_menu(
			array(
				'id'    => 'dna-tpl-name',
				'title' => $this->template_basename,
				'href'  => '#',
				'meta'  => array(
					'title' => $this->template
				)
			)
		);
	}
}