PHP Clone deep copy and shallow copy ccllone hdclone memberwiseclon-PHP Tutorial-php.cn

PHP Clone deep copy and shallow copy ccllone hdclone memberwiseclon

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Release： 2016-07-29 08:54:05

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Today when I was looking at the design patterns of Dahua, I saw the prototype pattern. It talked about deep copy and shallow copy, so I searched the PHP manual.
See how PHP implements deep copy and shallow copy.

<code><span><span>class</span><span>SubObject</span>
{</span><span>static</span><span>$instances</span> = <span>0</span>;
    <span>public</span><span>$instance</span>;

    <span>public</span><span><span>function</span><span>__construct</span><span>()</span>
    {</span><span>$this</span>->instance = ++ <span>self</span>::<span>$instances</span>;
    }

    <span>public</span><span><span>function</span><span>__clone</span><span>()</span>
    {</span><span>$this</span>->instance = ++<span>self</span>::<span>$instances</span>;
    }
}

<span><span>class</span><span>MyCloneable</span>
{</span><span>public</span><span>$object1</span>;
    <span>public</span><span>$object2</span>;

    <span>public</span><span><span>function</span><span>__clone</span><span>()</span>
    {</span><span>// 强制复制一份this->object， 否则仍然指向同一个对象</span><span>// 深复制[将自己的属性重新克隆一份]</span><span>$this</span>->object1 = <span>clone</span><span>$this</span>->object1;
        <span>// 浅复制[引用的还是原来，并没有生成新的]</span><span>//$this->object2 = clone $this->object2;</span>
    }

}

<span>$obj</span> = <span>new</span> MyCloneable();

<span>$obj</span>->object1 = <span>new</span> SubObject();
<span>$obj</span>->object2 = <span>new</span> SubObject();

<span>$obj2</span> = <span>clone</span><span>$obj</span>;

<span>print</span>(<span>"Original Object:\n"</span>);
print_r(<span>$obj</span>);

<span>print</span>(<span>"Clone Object:\n"</span>);
print_r(<span>$obj2</span>);</code>

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result

<code>Original Object:
MyCloneable Object
(
    [object1] => SubObject Object
        (
            [instance] => <span>1</span>
        )

    [object2] => SubObject Object
        (
            [instance] => <span>2</span>
        )

)
<span>Clone</span> Object:
MyCloneable Object
(
    [object1] => SubObject Object
        (
            [instance] => <span>3</span><span>//深复制 所以有+1</span>
        )

    [object2] => SubObject Object
        (
            [instance] => <span>2</span><span>//浅复制 并没有创建新的对象</span>
        )

)
</code>

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The above introduces PHP Clone deep copy and shallow copy, including clone and php content. I hope it will be helpful to friends who are interested in PHP tutorials.