gistfile1.txt

/*
* Gets the excerpt of a specific post ID or object
* @param - $post - object/int - the ID or object of the post to get the excerpt of
* @param - $length - int - the length of the excerpt in words
* @param - $tags - string - the allowed HTML tags. These will not be stripped out
* @param - $extra - string - text to append to the end of the excerpt
*/
function rcp_excerpt_by_id($post, $length = 50, $tags = '<a><em><strong><blockquote><ul><ol><li><p>', $extra = ' . . .') {
	
	if(is_int($post)) {
		// get the post object of the passed ID
		$post = get_post($post);
	} elseif(!is_object($post)) {
		return false;
	}
	$more = false;
	if(has_excerpt($post->ID)) {
		$the_excerpt = $post->post_excerpt;
	} elseif(strstr($post->post_content,'<!--more-->')) {
		$more = true;
		$length = strpos($post->post_content, '<!--more-->');
		$the_excerpt = $post->post_content;
	} else {
		$the_excerpt = $post->post_content;
	}

	$tags = apply_filters( 'rcp_excerpt_tags', $tags );

	if($more) {
		$the_excerpt = strip_shortcodes( strip_tags( stripslashes( substr($the_excerpt, 0, $length) ), $tags) );
	} else {
		$the_excerpt = strip_shortcodes(strip_tags(stripslashes($the_excerpt), $tags));
		$the_excerpt = preg_split('/\b/', $the_excerpt, $length * 2+1);
		$excerpt_waste = array_pop($the_excerpt);
		$the_excerpt = implode($the_excerpt);
		$the_excerpt .= $extra;
	}
	
	return wpautop($the_excerpt);
}