php文件系统函数问题！

我要在1.php上怎么写才能在log.txt上$msg里输出的是person.php的结果，就是把那个('调入文件成功')改为那个person.php的结果
//1.php
<?php
function writeLog($msg){
$logFile = 'log.txt';
date_default_timezone_set('Asia/Chongqing');
$msg = date('Y-m-d H:i:s').' >>> '.$msg."\r\n";
file_put_contents($logFile,$msg,FILE_APPEND );
require_once('person.php');
}
writeLog('调入文件成功');
?>

//person.php
<?php
class Person{
public $name;
public $age;
function construct($name,$age){
$this->name = $name;
$this->age = $age;
}
function show() {
echo "my name is ".$this->name." ";

}
}
$sxd=new Person();
$sxd->name="sxd";
$sxd->age=22;
$sxd->show();
echo "age is ".$sxd->age;
?>

可以利用ob缓存机制解决这个问题：

<?php

function writeLog($msg){

ob_start();

require_once('person.php');

$msg = ob_get_clean();

$logFile = 'log.txt';

date_default_timezone_set('Asia/Chongqing');

$msg = date('Y-m-d H:i:s').' >>> '.$msg."\r\n";

file_put_contents($logFile,$msg,FILE_APPEND );

}

writeLog('调入文件成功');

?>