[namespace]PHP命名空间的动态访问 & 使用技巧

<span>/*</span><span>
|----------------------------------------
|一.动态访问命名空间的元素
|@黑眼诗人 <www.farwish.com>
|----------------------------------------
</span><span>*/</span><span>
namespace me\poet;

</span><span>function</span><span> test()
{
    </span><span>echo</span> '1111'<span>;
}

</span><span><span>$fun</span> = 'test';</span><span>//</span><span>不能这么用，最后$fun()无法动态调用到test():<strong>Fatal error</strong>: Call to undefined function test()</span>

<span>$fun</span> = '\me\poet\test';<span>//</span><span>正确

//$fun = 'me\poet\test';//正确</span>

<span>$fun</span><span>();<br />

</span><span>//</span><span>也就是说，动态调用必须是 限定名称 或 完全限定名称（概念参考：PHP命名空间的使用基础）</span>

<span>/*</span><span>
|-------------------------------------
|二.魔术常量 和 操作符
|-------------------------------------
</span><span>*/</span><span>
namespace me\poet;

</span><span>function</span><span> test()
{
    </span><span>echo</span> '1'<span>;
}

</span><span>echo</span> __NAMESPACE__;　<span>//</span><span>魔术常量:命名空间的名称（输出 me\poet）

//namespace操作符：显式访问当前命名空间或子命名空间中的元素，等价于类中的self操作符</span>
\<span>me\poet\test();

namespace\test();

//上两行代码等价。</span>

<span>/*</span><span>
|-------------------------------------------
|三.别名、导入 和 全局空间（含多个例子）
|-------------------------------------------
</span><span>*/</span><span>
namespace ws\weichen\www;

</span><span>use</span> ws\weichen\www <span>as</span> poet;<span>//</span><span>定义别名poet

//use ws\weichen\www; //不加as，则取最后的作为别名（www）</span>

<span>function</span><span> demo()
{
    </span><span>echo</span> '1'<span>;
}

\ws\weichen\www\demo();

poet\demo();

</span><span>//</span><span>www\demo();　　　　//不加as的情况，则这样调用

//以上三行代码效果一样。

//按规则（ws\weichen\www）命名的好处：若更换域名，只要把前缀名称改了就可以，不影响后面代码中别名www的使用。</span>

/*--------------------------------------------------------*/<br />
<span>/*</span><span> 导入 </span><span>*/<br /></span>
<span>include</span> 'hello.class.php'<span>;

</span><span>use</span><span> \ws\weichen\www;

</span><span>use</span><span> \Hello;
<br />/*--------------------------------------------------------*/<br />
</span><span>/*</span><span> 支持多个use语句 </span><span>*/<br /></span>
<span>use</span> \nihao\shijie <span>as</span> hello,<span> \ws\weichen\www;

/*--------------------------------------------------------*/<br />
</span><span>/*</span><span> 全局空间:反斜线调用 </span><span>*/</span><span>
<br />namespace A\B\C;
</span><span>//</span><span>这个函数是 A\B\C\fopen();</span>
<span>function</span> <span>fopen</span><span>()
{
    </span><span>$f</span> = \<span>fopen</span>('demo.txt');<span>//</span><span>调用全局fopen函数</span>
    <span>return</span> <span>$f</span><span>;
}</span>