PHP中new static()与new self()的比较-php手册-PHP中文网

PHP中new static()与new self()的比较

WBOY

发布： 2016-08-20 08:47:38

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　　今天在coding的时候，发现了 new static(),觉得实例化的地方不是应该是 new self()吗？查询了一下才知道两者的区别：

　　1）在有子类集成的时候，两者的表现不一样

　　2）php 5.2及以下的版本不支持 new static()的语法

具体解释如下：

self - 就是这个类，是代码段里面的这个类。

static - PHP 5.3加进来的只得是当前这个类，有点像$this的意思，从堆内存中提取出来，访问的是当前实例化的那个类，那么 static 代表的就是那个类。

还是看看老外的专业解释吧：

self refers to the same class whose method the new operation takes place in.

static in PHP 5.3's late static bindings refers to whatever class in the hierarchy which you call the method on.

In the following example, B inherits both methods from A. self is bound to A because it's defined in A's implementation of the first method, whereas static is bound to the called class (also see  get_called_class() ).

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上代码：

<span style="color: #008080;"> 1</span> <span style="color: #0000ff;">class</span><span style="color: #000000;"> Person {
</span><span style="color: #008080;"> 2</span>   <span style="color: #0000ff;">public</span> <span style="color: #0000ff;">static</span> <span style="color: #0000ff;">function</span><span style="color: #000000;"> get_self() {
</span><span style="color: #008080;"> 3</span>     <span style="color: #0000ff;">return</span> <span style="color: #0000ff;">new</span><span style="color: #000000;"> self();
</span><span style="color: #008080;"> 4</span> <span style="color: #000000;">  }
</span><span style="color: #008080;"> 5</span>  
<span style="color: #008080;"> 6</span>   <span style="color: #0000ff;">public</span> <span style="color: #0000ff;">static</span> <span style="color: #0000ff;">function</span><span style="color: #000000;"> get_static() {
</span><span style="color: #008080;"> 7</span>     <span style="color: #0000ff;">return</span> <span style="color: #0000ff;">new</span> <span style="color: #0000ff;">static</span><span style="color: #000000;">();
</span><span style="color: #008080;"> 8</span> <span style="color: #000000;">  }
</span><span style="color: #008080;"> 9</span> <span style="color: #000000;">}
</span><span style="color: #008080;">10</span>  
<span style="color: #008080;">11</span> <span style="color: #0000ff;">class</span> WangBaoqiang <span style="color: #0000ff;">extends</span><span style="color: #000000;"> Person{}
</span><span style="color: #008080;">12</span>  
<span style="color: #008080;">13</span> <span style="color: #0000ff;">echo</span> <span style="color: #008080;">get_class</span>(WangBaoqiang::get_self()); <span style="color: #008000;">//</span><span style="color: #008000;"> Person</span>
<span style="color: #008080;">14</span> <span style="color: #0000ff;">echo</span> <span style="color: #008080;">get_class</span>(WangBaoqiang::get_static()); <span style="color: #008000;">//</span><span style="color: #008000;"> WangBaoqiang</span>
<span style="color: #008080;">15</span> <span style="color: #0000ff;">echo</span> <span style="color: #008080;">get_class</span>(Person::get_static()); <span style="color: #008000;">//</span><span style="color: #008000;"> Person</span>

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但是如果想让子类使用 get_class时，返回的也是当前子类的名称（'wangbaoqiang'）,该怎么做呢。

<?<span style="color: #000000;">php
</span><span style="color: #0000ff;">class</span><span style="color: #000000;"> Person {
  </span><span style="color: #0000ff;">public</span> <span style="color: #0000ff;">function</span><span style="color: #000000;"> create1() {
    </span><span style="color: #800080;">$class</span> = <span style="color: #008080;">get_class</span>(<span style="color: #800080;">$this</span><span style="color: #000000;">);
　　　　</span><span style="color: #0000ff;">return</span> <span style="color: #0000ff;">new</span> <span style="color: #800080;">$class</span><span style="color: #000000;">();
  }
  </span><span style="color: #0000ff;">public</span> <span style="color: #0000ff;">function</span><span style="color: #000000;"> create2() {
    </span><span style="color: #0000ff;">return</span> <span style="color: #0000ff;">new</span> <span style="color: #0000ff;">static</span><span style="color: #000000;">();
  }
}
 
</span><span style="color: #0000ff;">class</span> WangBaoqiang <span style="color: #0000ff;">extends</span><span style="color: #000000;"> Person {
 
}
 
</span><span style="color: #800080;">$wangBaoQiang</span> = <span style="color: #0000ff;">new</span><span style="color: #000000;"> WangBaoqiang();
</span><span style="color: #008080;">var_dump</span>(<span style="color: #008080;">get_class</span>(<span style="color: #800080;">$wangBaoQiang</span>->create1()), <span style="color: #008080;">get_class</span>(<span style="color: #800080;">$wangBaoQiang</span>-><span style="color: #000000;">create2()));
 
</span><span style="color: #008000;">/*</span><span style="color: #008000;">
The result 
string(1) "WangBaoqiang"
string(1) "WangBaoqiang"
</span><span style="color: #008000;">*/</span>

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欢迎大家，批评指正，谢谢