Detailed explanation of php namespace usage

This article mainly introduces the usage of namespace use in PHP, and analyzes the definition and usage skills of namespace in PHP in the form of examples. Friends in need can refer to it. I hope to be helpful.

The details are as follows:

It feels a bit outdated to say this now, but I feel that not many people use namespace, probably because they are not used to it.

Class organizes functions one by one, and namespace can be understood as organizing classes, functions, etc. in an orderly manner. Personally, I think the main advantages of namespace are

First, it can better manage the code
Second, with more files, it can avoid duplicate names of classes and functions
Third, the code is readable Enhanced performance

1. Define namespace

namespace userCenter;
//php代码
namespace userCenter\register;
//php代码
namespace userCenter\login {
 //php代码
}

The namespace cannot be nested or declared multiple times in the same code (only will be recognized last time). However, you can define multiple namespaced codes in the same file. It is more appropriate to define a namespace for each file (it can be the same namespace).

2. Call namespace

\userCenter\register; //绝对调用
userCenter\login; //相对调用
use userCenter\register; //引用空间
use userCenter\register as reg; //引用空间并加别名

3. Example

login. class.php

<?php
namespace userCenter;
function check_username(){
 echo "login OK<br>";
}
class login{
 public function save(){
 echo "login had saved<br>";
 }
}
?>

regist.class.php

##

<?php
namespace userCenter\regist
{
 function check_username() {
 echo "regist OK<br>";
 }
 class regist{
 public function save(){
 echo "regist had saved<br>";
 }
 }
}
?>

test.php

<?php
require "login.class.php";
require "regist.class.php";
use userCenter\regist; //使用use调用空间
use userCenter\regist as reg; //as定义别名
echo \userCenter\check_username(); //绝对调用
$login = new \userCenter\login();
echo $login->save();
echo regist\check_username(); //相对调用
echo reg\check_username(); //别名调用
$regist = new reg\regist();
echo $regist->save();

Using use is better than absolute calling. It is like adding a prefix to class, function, etc., so that it looks clearer.

Related recommendations:

A brief analysis of namespace related concepts in php

PHP namespace and automatically loaded classes

Basics of using PHP namespace

The above is the detailed content of Detailed explanation of php namespace usage. For more information, please follow other related articles on the PHP Chinese website!