php 魔术方法 __sleep __wakeup __toString __debuginfo

__sleep():

使用serialize()序列化的时候，会检测类中是否有__sleep()魔术方法，有的话会先调用__sleep()，返回一个包含对象中所有需要序列化的变量名称的数组

<code><span><?php </span><span><span>class</span><span>test</span>{</span><span>public</span><span>$name</span>=<span>'demon'</span>;

    <span>private</span><span>$age</span>=<span>'19'</span>;

    <span>public</span><span><span>function</span><span>__sleep</span><span>()</span>{</span><span>return</span> [<span>'name'</span>];
    }  
}

<span>$test</span> = <span>new</span> test();
<span>echo</span> serialize(<span>$test</span>);
<span>//输出结果：O:4:"test":1:{s:4:"name";s:5:"demon";}</span></span></code>

__wakeup()

使用serialize()序列化的时候，会检测类中是否有__wakeup()魔术方法，有的话会先调用__wakeup()，执行一些初始化操作

<code><span><?php </span><span><span>class</span><span>test</span>{</span><span>public</span><span>$name</span>=<span>'demon'</span>;

    <span>private</span><span>$age</span>=<span>'19'</span>;

    <span>public</span><span><span>function</span><span>say</span><span>()</span>{</span><span>echo</span><span>"反序列化"</span>;
    }

    <span>public</span><span><span>function</span><span>__wakeup</span><span>()</span>{</span><span>$this</span>->say();
    }   
}

<span>$test</span> = <span>new</span> test();
unserialize(serialize(<span>$test</span>));
<span>//输出结果：反序列化</span></span></code>

__toString()

__toString()用于一个类被当做字符串使用时的回应，只能返回一个字符串

<code><span><?php </span><span><span>class</span><span>test</span>{</span><span>public</span><span>$name</span>=<span>'demon'</span>;

    <span>private</span><span>$age</span>=<span>'19'</span>;

    <span>public</span><span><span>function</span><span>__toString</span><span>()</span>{</span><span>return</span><span>'test'</span>;
    } 
}

<span>$test</span> = <span>new</span> test();
<span>echo</span><span>$test</span>;
<span>//输出结果：test</span></span></code>

__debuginfo()

__debuginfo() 是php5.6增加的特性，var_dump()一个类时的回应，返回一个包含对象属性的数组

<code><span><?php </span><span><span>class</span><span>test</span>{</span><span>public</span><span>$name</span>=<span>'demon'</span>;

    <span>private</span><span>$age</span>=<span>'19'</span>;

    <span>public</span><span><span>function</span><span>__debuginfo</span><span>()</span>{</span><span>return</span> [<span>'name'</span>];
    }

}

<span>$test</span> = <span>new</span> test();
var_dump(<span>$test</span>);
<span>//输出结果：object(test)#1 (1) { [0]=> string(4) "name" }</span></span></code>

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