WordPress Plugin template with conditional style/script loading

plugin-template.php

<?php
/*
Plugin Name: Plugin Name
Description: Description
Version:     0.1
Author:      White Rock Design
Author URI:  http://keithdevon.com
*/

// block direct access
defined( 'ABSPATH' ) or die( 'No script kiddies please!' );


// load the plugin script if the $add_sex_degress_script global variable is true

add_action('init', 'register_plugin_script');
add_action('wp_footer', 'print_plugin_script');

function register_plugin_script() {
	wp_register_script('plugin-script', plugins_url('plugin-script.js', __FILE__), array('jquery'), '1.0', true);
}

function print_plugin_script() {
	global $add_plugin_script;

	if ( ! $add_plugin_script )
		return;

	wp_print_scripts('plugin-script');
}


//[my_shortcode]
function my_shortcode_func( $atts ){

	// set to true so that the plugin script is loaded when the shortcode is called
	global $add_plugin_script;
	$add_plugin_script = true;

	// load the stylesheet in the head
	$plugin_url = plugin_dir_url( __FILE__ );
	$css_url = $plugin_url . 'style.css';

	$html = "<script>jQuery(document).ready(function($) {
	$('head').prepend($('<link>').attr({
		rel: 'stylesheet',
		type: 'text/css',
		media: 'screen',
		href: '" . $css_url . "'
		}));
	});
	</script>";

	$html .= '<h1>Hello World!</h1>';

	return $html;
}
add_shortcode( 'my_shortcode', 'my_shortcode_func' );