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PHP命名空间可以解决哪些问题

Jun 06, 2016 pm 08:23 PM
phpNamespaces

PHP命名空间可以解决哪些问题

PHP 命名空间(namespace)

PHP 命名空间(namespace)是在PHP 5.3中加入的,如果你学过C#和Java,那命名空间就不算什么新事物。 不过在PHP当中还是有着相当重要的意义。

PHP 命名空间可以解决以下两类问题:

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。

为很长的标识符名称(通常是为了缓解第一类问题而定义的)创建一个别名(或简短)的名称,提高源代码的可读性。

定义命名空间

默认情况下,所有常量、类和函数名都放在全局空间下,就和PHP支持命名空间之前一样。

命名空间通过关键字namespace 来声明。如果一个文件中包含命名空间,它必须在其它所有代码之前声明命名空间。语法格式如下;

namespace MyProject;
const CONNECT_OK = 1;
class Connection { /* ... */ }
function connect() { /* ... */  }
namespace AnotherProject;
const CONNECT_OK = 1;
class Connection { /* ... */ }
function connect() { /* ... */  }
?>

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