为什么某些PHP对象可以转换为字符串

Question

I was looking into PHP tidy and I saw the following code

$tidy = new tidy;
$tidy->parseString($html, $config, 'utf8');
$tidy->cleanRepair();
// Output
echo $tidy;

Tidy here is an object. Why isn't this throwing a Catchable fatal error: Object of class tidy could not be converted to string error???

Answer 1

我不熟悉整洁，但我的猜测是，该对象实现了魔术方法__toString（），如下所述： http : //php.net/manual/en/language.oop5.magic.php#object。弦