PHP 命名空间和“使用”
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PHP namespaces and "use"
提问by Shawn Northrop
I am having a little trouble with namespaces and the usestatements.
我在命名空间和use语句方面遇到了一些麻烦。
I have three files: ShapeInterface.php, Shape.phpand Circle.php.
我有三个文件：ShapeInterface.php,Shape.php和Circle.php.
I am trying to do this using relative paths so I have put this in all of the classes:
我试图使用相对路径来做到这一点，所以我把它放在所有的类中：
namespace Shape;
In my circle class I have the following:
在我的圈子课中，我有以下内容：
namespace Shape;
//use Shape;
//use ShapeInterface;
include 'Shape.php';
include 'ShapeInterface.php';
class Circle extends Shape implements ShapeInterface{ ....
If I use the includestatements I get no errors. If I try the usestatements I get:
如果我使用这些include语句，我不会出错。如果我尝试use我得到的陈述：
Fatal error: Class 'Shape\Shape' not found in /Users/shawn/Documents/work/sites/workspace/shape/Circle.php on line 8
致命错误：在第 8 行的 /Users/shawn/Documents/work/sites/workspace/shape/Circle.php 中找不到类“Shape\Shape”
Could someone please give me a little guidance on the issue?
有人可以就这个问题给我一些指导吗？
回答by cmbuckley
The useoperatoris for giving aliases to names of classes, interfaces or other namespaces. Most usestatements refer to a namespace or class that you'd like to shorten:
该use运算符用于为类、接口或其他命名空间的名称提供别名。大多数use语句引用您想要缩短的命名空间或类：
use My\Full\Namespace;
is equivalent to:
相当于：
use My\Full\Namespace as Namespace;
// Namespace\Foo is now shorthand for My\Full\Namespace\Foo
If the useoperator is used with a class or interface name, it has the following uses:
如果use运算符与类或接口名称一起使用，则它具有以下用途：
// after this, "new DifferentName();" would instantiate a My\Full\Classname
use My\Full\Classname as DifferentName;
// global class - making "new ArrayObject()" and "new \ArrayObject()" equivalent
use ArrayObject;
The useoperator is not to be confused with autoloading. A class is autoloaded (negating the need for include) by registering an autoloader (e.g. with spl_autoload_register). You might want to read PSR-4to see a suitable autoloader implementation.
use不要将运算符与autoloading混淆。include通过注册一个自动加载器（例如使用spl_autoload_register）来自动加载一个类（不需要）。您可能需要阅读PSR-4以查看合适的自动加载器实现。
回答by Charlie
If you need to order your code into namespaces, just use the keyword namespace:
如果您需要将代码排序到命名空间中，只需使用关键字namespace：
file1.php
文件1.php
namespace foo\bar;
In file2.php
在 file2.php 中
$obj = new \foo\bar\myObj();
You can also use use. If in file2 you put
您也可以使用use. 如果在 file2 你把
use foo\bar as mypath;
use foo\bar as mypath;
you need to use mypathinstead of baranywhere in the file:
您需要使用mypath而不是bar文件中的任何位置：
$obj = new mypath\myObj();
Using use foo\bar;is equal to use foo\bar as bar;.
使用use foo\bar;等于use foo\bar as bar;。
