render-php-file.php

<?php

function renderPhpFile($filename, $vars = null)
{
  if (is_array($vars) && !empty($vars))
  {
    extract($vars);
  }
  ob_start();
  include $filename;
  return ob_get_clean();
}

// usage
echo renderPhpFile('views/templates/index.php', $data_for_view);