PHP之克隆clone

浅克隆：只是克隆对象中的非对象非资源数据，即对象中属性存储的是对象类型，则会出现克隆不完全

<code><span><span><?php </span><span><span>class</span><span>B</span>{</span><span>public</span><span>$val</span> = <span>10</span>;
}

<span><span>class</span><span>A</span>{</span><span>public</span><span>$val</span> = <span>20</span>;
    <span>public</span><span>$b</span>;
    <span>public</span><span><span>function</span><span>__construct</span><span>()</span>{</span><span>$this</span>->b = <span>new</span> B();
    }
}

<span>$obj_a</span> = <span>new</span> A();
<span>$obj_b</span> = <span>clone</span><span>$obj_a</span>;
<span>$obj_a</span>->val = <span>30</span>;
<span>$obj_a</span>->b->val = <span>40</span>;

var_dump(<span>$obj_a</span>);
<span>echo</span><span>'<br>'</span>;
var_dump(<span>$obj_b</span>);</span></span></code>

深克隆：一个对象的所有属性数据都彻底的复制，需要使用魔术方法__clone()，并在里面实现深度克隆

<code><span><span><?php </span><span><span>class</span><span>B</span>{</span><span>public</span><span>$val</span> = <span>10</span>;
}

<span><span>class</span><span>A</span>{</span><span>public</span><span>$val</span> = <span>20</span>;
    <span>public</span><span>$b</span>;
    <span>public</span><span><span>function</span><span>__construct</span><span>()</span>{</span><span>$this</span>->b = <span>new</span> B();
    }
    <span>public</span><span><span>function</span><span>__clone</span><span>()</span>{</span><span>$this</span>->b = <span>clone</span><span>$this</span>->b;
    }
}

<span>$obj_a</span> = <span>new</span> A();
<span>$obj_b</span> = <span>clone</span><span>$obj_a</span>;
<span>$obj_a</span>->val = <span>30</span>;
<span>$obj_a</span>->b->val = <span>40</span>;

var_dump(<span>$obj_a</span>);
<span>echo</span><span>'<br>'</span>;
var_dump(<span>$obj_b</span>);</span></span></code>

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