Using Namespaces, Aliases, Traits, and Closures in PHP

This article provides practical examples of several advanced PHP features, including namespace declarations, aliasing with the use keyword, trait inclusion, and variable capture in anonymous functions.

1. Namespace usage

<?php
namespace admin\controller;
use \core\controller; //引入命名空间
class ArticleController extends Controller{
    public function index(){
        
    }
}
?>

2. Alias keyword

<?php
namespace space;
function display(){}
class Man{}
const PI = 3.14;

namespace space1;
class Man{};
//use space\Man; //错误：当前空间已经存在Man
use space\Man as M;
use function space\display as dis;
use const space\PI as D;
?>

3. Trait inclusion

<?php
trait A{
    function testTrait(){
        echo 'This is Trait A!';
    }
}
class B {
    use A;
}
$b = new B();
$b->testTrait();
?>

4. Anonymous function with variable capture

<?php
function F1(){
    $ok = "HelloWorld";
    $a = function() use ($ok) {
        echo "$ok";
    };
    $a();
}
F1();
?>