Example of a template function in PHP

simple-php-template.php

<?php
/**
 * Simple PHP Templating function
 *
 * @param $names  - string|array Template names
 * @param $args   - Associative array of variables to pass to the template file.
 * @return string - Output of the template file. Likely HTML.
 */
function template( $names, $args ){
  // allow for single file names
  if ( !is_array( $names ) ) { 
    $names = array( $names ); 
  }

  // try to find the templates
  $template_found = false;
  foreach ( $names as $name ) {
    $file = __DIR__ . '/templates/' . $name . '.php';

    if ( file_exists( $file ) ) {
      $template_found = $file;
      // stop after the first template is found
      break;
    }
  }

  // fail if no template file is found
  if ( ! $template_found ) {
    return '';
  }

  // Make values in the associative array easier to access by extracting them
  if ( is_array( $args ) ){
    extract( $args );
  }

  // buffer the output (including the file is "output")
  ob_start();
    include $template_found;
  return ob_get_clean();
}

Source blog post: http://www.daggerhart.com/create-simple-php-templating-function/