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怎么理解php中命名空间概念

Jun 13, 2016 pm 12:23 PM
include php sub

如何理解php中命名空间概念

PHP中命名空间的本质是容器,可以起到封装的作用。

在这个容器中中我们可以放入变量函数


php命名空间概念的理解可以类比于文件目录在操作系统中目录用来将相关文件分组,对于目录中的文件来说,它就扮演了命名空间的角色。


上面root文件夹下包含两个子文件夹sub1和sub2,sub1和sub2就相当于两个容器,起到封装的作用,可以在两个文件下定义相同的文件sub2.php,因为他们是互不干扰的。要在sub1.php文件中引用同级目录下sub2.php中的内容,直接包含进来就行了(include('sub2.php')),但在sub1.php中引用sub2下的sub2.php中的内容,就要使用到文件分隔符,具体来说是include('../sub2/sub2.php')。

php中命名空间的相互引用也要用到类似于文件分隔符一样的东西。

PHP命名空间的实际应用:

命名空间可以解决下面两个问题:

(1)用户编写的代码与PHP内部的类/函数/常量或第三方类/函数/常量之间的名字冲突。

(2)为很长的标识符创建一个别名,提高代码的可读性,减少代码的编写量。


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