PHP导入类和use关键字

Question

I don't use so far PHP use word, but must now... :)

index.php content:

require_once 'Classes/MainClass.php';
$obj = new Main();
echo $obj->test();

Classes/MainClass.php

<?php
use AdminFrontEnd;

class Main {
    function test(){
        return new AdminFrontEnd("debug");
    }
} 

AdminFrontEndClass.php content:

<?php
class AdminFrontEnd {
    function __constuctor($test){
        echo $test;
    }
} 

and final, following error:

Fatal error: Class 'AdminFrontEnd' not found in Classes/MainClass.php on line 10

Answer 1

As per comment from @deceze, you will either need to explicitly import the additional class, using a require statement, or autoload.

The use statement is for aliasing a class, and as @deceze said, can be used to pull in a class from a different namespace, or to avoid a class conflict.

Having a class called 'Main' may not be ideal. Is it a singleton, or will there be multiple 'Main's?
Maybe this class would be better named 'App'.

In the longer term you will want to learn about using namespaces, so that if you use other people's classes and plugins, you won't have conflict. I've added a solution, and also some broader info below.

To get you off the hook:

Classes/MainClass.php

<?php

require_once 'Classes/AdminFrontEnd.php';

class Main {   /*   etc...  */ 

Further reading I would recommend:

Examples for creating an autoload:

http://php.net/manual/en/language.oop5.autoload.php

You'll probably want to learn about namespaces too:

http://php.net/manual/en/language.namespaces.php

I also highly recommend reading about interoperability coding standards. It's a lot to take in to begin with, but it will help you understand the logic behind using namespaces, and autoloaders.

http://www.php-fig.org/