<?php
/* Short code [a href="pageId" class"clasName"]link[/a] */


/*If you check “add paragraphs automatically” on the widget, WordPress will apply the autop filter — the one that turns your line breaks into paragraph and break tags. If a shortcode is on its own line, it would normally get wrapped in a paragraph tag. The first line prevents that from happening.

thanks to http://sillybean.net/2010/02/using-shortcodes-everywhere/
*/

add_filter( 'widget_text', 'shortcode_unautop');

//Add shortcode functionality to widgets
add_filter('widget_text', 'do_shortcode');


function a_func($atts, $content) {
     extract(shortcode_atts(array(
	      'href' => ' ',
	      'class' => ' ',
     ), $atts));
	 	
	$theLink = '<a class="'. $class .'" href="'. get_permalink($href) .'">'. $content .'</a>';
	 
     return "{$theLink}";
}

add_shortcode('a', 'a_func');

?>

<?php
/* Short code [a href="pageId" class"clasName"]link[/a] */

//Add shortcode functionality to widgets
add_filter('widget_text', 'do_shortcode');


function a_func($atts, $content) {
     extract(shortcode_atts(array(
	      'href' => ' ',
	      'class' => ' ',
     ), $atts));
	 	
	$theLink = '<a class="'. $class .'" href="'. get_permalink($href) .'">'. $content .'</a>';
	 
     return "{$theLink}";
}

add_shortcode('a', 'a_func');

?>

Make shortcode for dynamics links for widgets in wordpress

PHP