Restrict content piece by role - Protection message in content?

Posted: asked May 19 at 10:16 - Source : stackoverflow

I use below function (Nothing here is protection message):

function show_user_content($atts,$content = null){
  global $post;
    if (current_user_can('subscriber')){
    return $content;
  }
    return "Nothing here";
}
add_shortcode('RESTRICTROLE','show_user_content');

Then in post content:

[RESTRICTROLE]some word for subscriber[/RESTRICTROLE]

I need to be able to write the protection message in post content instead of in function.

My goal is to use multiple protection message by using single function.