ช่วยหน่อยค่ะ ต้องเขียนฟังชั่นยังไงค่ะ ถึงจะเรียกใช้ $_['heading_title'] เป็น $heading_title แบบนี้ได้

<?php
define("CONSTANT", "Hello world.");
echo CONSTANT; // outputs "Hello world."
echo Constant; // outputs "Constant" and issues a notice.

define("GREETING", "Hello you.", true);
echo GREETING; // outputs "Hello you."
echo Greeting; // outputs "Hello you."

?>

$_['hello'] = "world";
$_['thaicreate'] = "second to none";

extract($_);
echo "hello ".$hello;
echo "<br />";
echo "thaicreate ".$thaicreate;

foreach ($_ as $key=>$val) $$key = $val;

  	public function load($filename) {
		$file = DIR_LANGUAGE . $this->directory . '/' . $filename . '.php';
    	
		if (file_exists($file)) {
			$_ = array();
	  		
			require($file);
		
			$this->data = array_merge($this->data, $_);
			
			return $this->data;
		}
		
		$file = DIR_LANGUAGE . $this->default . '/' . $filename . '.php';
		
		if (file_exists($file)) {
			$_ = array();
	  		
			require($file);
		
			$this->data = array_merge($this->data, $_);
			
			return $this->data;
		} else {
			trigger_error('Error: Could not load language ' . $filename . '!');
			exit();
		}
  	}