Php file inclusion bug.

//index.php
<?php
require_once('function.php');
require_once('config.php');

echo $myHomeVarable;
doTestFuntion();

?>

//function.php
<?php
function doTestFuntion()
{
    //require_once('config.php');// Causes PHP Notice:  Undefined variable: myFunctionVarable in /srv/www/htdocs/fwstest/function.php on line 7
    require('config.php');//Causes PHP Fatal error:  Cannot redeclare trapFunction() (previously declared in /srv/www/htdocs/fwstest/config.php:8) in /srv/www/htdocs/fwstest/config.php on line 9


    echo $myFunctionVarable;
}
?>

//config.php
<?php

$myHomeVarable = 'Home Works';
$myFunctionVarable = 'Function Works';

function trapFunction()
{
echo'boo';
}

?>