<?php
/* functions.php */

add_action( 'after_setup_theme', array ( 'My_Theme_Class', 'init' ) );

class My_Theme_Class
{
	protected static $instance = NULL;

	public static function init()
	{
		NULL === self::$instance && self::$instance = new self;
	}

	public static function get_instance()
	{
		// just in case the object doesn’t exist anymore
		self::init();
		return self::$instance;
	}

	public function __construct()
	{
		// do something
	}

	/**
	 * Usage: My_Theme_Class::get_instance()->test()

add_action('admin_enqueue_scripts', 'wpse49449_admin_scripts',10,1);
function wpse49449_admin_scripts($hook){
	$screen = get_current_screen();
	$post_type = $screen->post_type;
		if ( ('post-new.php' == $hook || 'post.php' == $hook) && $post_type == 'post' ){
			wp_register_script('my_md_convert', '/wp-content/themes/2012-aahan/pagedown/Markdown.Converter.js',array(),'1.1' );
			wp_register_script('my_md_sanit', '/wp-content/themes/2012-aahan/pagedown/Markdown.Sanitizer.js',array(),'1.1' );
			wp_register_script('my_md_edit', '/wp-content/themes/2012-aahan/pagedown/Markdown.Editor.js',array…