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self::$instance null || !(self::$instance instanceof Tpl

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Release： 2016-06-23 13:12:54
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self::$instance === null || !(self::$instance instanceof Tpl）
这句话是什么意思,有点看不明白


回复讨论(解决方案)

instance 实例

self::$instance 表示类的一个静态属性
在这里表示存储了一个实例化后的对象

self::$instance === null 是没有实例化的意思

self::$instance instanceof Tpl 表示 self::$instance 保存的对象隶属于类 Tpl
!(self::$instance instanceof Tpl) 就是对象不是从 Tpl 或其派生类产生的

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self::$instance null || !(self::$instance instanceof Tpl
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