您真的不需要担心清理PHP中的变量声明，它的垃圾回收会为您处理所有这些事情.您的__destruct()方法主要用于关闭持久连接.

You really don't need to worry about cleaning up your variable declarations in PHP, its garbage collection takes care of all of that for you. Your __destruct() methods are primarily for things like closing persistent connections.