如何通过前端控制器调用功能？

I have a function that displays some artists names. I need to call this on my main page without messing up my security, how can I do this correctly? my setup looks like this:

Index.php (Front End Controller, calls the homepage when passed the case 'main')

case 'main' go to Main.php

Main.php (Call to function goes here)

displayArtists()

PublicController.php (Function lives here)

displayArtists() {
  //This code displays the artists
}