How to introduce another space element in a namespace?

Space introduction method: use use keywords

<?php
namespace n1;
class OK{};
namespace n2;

//一种方式
new \n1\OK();

//第二种方式  
use n1\OK;
new OK();
?>

The elements introduced by space are classes by default. If you want to introduce other elements, you must use the corresponding keywords : function and const (if you need to introduce multiple elements of the same type, you need to use "," to separate them)

<?php
namespace n1;
class OK{};
function display(){
    echo "display";
}
const P=10;
const  A=11;
namespace n2;
use n1\OK;              //引入类
use function n1\display;             //引入函数
use const   n1\A,n1\P;       //引入常量,可以同时引入多个

display();
echo P;
new OK();
?>

If You need to add multiple elements at the same time

<?php
namespace n1;
class OK{};
function display(){
    echo "n1中的display";
}
const P=10;
const  A=11;

namespace n2;
    use n1\{
    OK,
    const P,
    const A
};	
?>

If the introduced element already exists in the current space, there will be duplicate names. The solution is to use aliasesas Keyword for renaming

<?php
namespace n1;
class OK{};
function display(){
    echo "n1中的display";
}
const P=10;
const  A=11;

namespace n2;
function display(){
    echo "n2中的display";
}

use n1\OK;              //引入类
use function n1\display as display2;//引入函数
use const    n1\P,n1\A;       //引入常量


display2();
echo P." ".A;
new OK();
?>

If all elements in a space need to be introduced, you can also directly introduce space

<?php
namespace n1\n2;
class OK{
    public function __construct()
    {
        echo __NAMESPACE__."<br>";
    }
}

namespace n2;
class OK{
    public function __construct()
    {
        echo __NAMESPACE__."<br>";
    }
}
//引入空间
use n1\n2;

new OK();                       //访问的是n2\OK
new n2\OK();                //使用引入空间的最后一级空间访问

?>

Recommended: php tutorial ,php video tutorial

The above is the detailed content of How to introduce another space element in a namespace?. For more information, please follow other related articles on the PHP Chinese website!