Usage and examples of use keyword in PHP

The use keyword in PHP is a keyword used to import namespaces or use aliases, which allows us to use and reference classes, functions, constants, etc. more conveniently in the code. The usage and examples of the use keyword will be introduced below.

1. Import namespace
After using the namespace keyword to define a namespace, you can import classes, functions, constants, etc. in other namespaces through the use keyword so that they can be directly used in the current namespace. Use without writing the full namespace path.

Example 1:

<?php
namespace MyNamespace;

use OtherNamespaceClassName;
use function OtherNamespaceunction_name;
use const OtherNamespaceCONST_NAME;

$object = new ClassName(); // 在当前命名空间中使用导入的类

$value = function_name(); // 在当前命名空间中使用导入的函数

echo CONST_NAME; // 在当前命名空间中使用导入的常量
?>

Example 2:

<?php
namespace MyNamespace;

use OtherNamespace{ClassName, function_name, CONST_NAME}; // 一次导入多个类、函数、常量

$object = new ClassName(); // 在当前命名空间中使用导入的类

$value = function_name(); // 在当前命名空间中使用导入的函数

echo CONST_NAME; // 在当前命名空间中使用导入的常量
?>

2. Use aliases
In PHP, we can use aliases to name classes, functions, constants, etc. A name that's easier to remember so it's easier to use in code.

Example 3:

<?php
use SomeNamespaceLongClassName as ShortClassName; // 给类起别名

use function SomeNamespace_very_long_function_name as short_function_name; // 给函数起别名

use const SomeNamespaceLONG_CONST_NAME as SHORT_CONST_NAME; // 给常量起别名

$object = new ShortClassName(); // 使用别名创建对象

$value = short_function_name(); // 使用别名调用函数

echo SHORT_CONST_NAME; // 使用别名输出常量
?>

Example 4:

<?php
use SomeNamespace{LongClassName as ShortClassName, a_very_long_function_name as short_function_name, LONG_CONST_NAME as SHORT_CONST_NAME}; // 一次给多个类、函数、常量起别名

$object = new ShortClassName(); // 使用别名创建对象

$value = short_function_name(); // 使用别名调用函数

echo SHORT_CONST_NAME; // 使用别名输出常量
?>

Summary:
By using the use keyword in PHP, we can easily import into other namespaces classes, functions, constants, etc., and give them aliases to simplify code writing and writing. The above examples show the usage and examples of importing namespaces and using aliases. I hope it will be helpful to you in PHP development.

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