php `use` class in parent folder

问题

I have installed Propel ORM with Composer but I cannot create a new model as the PHP script is not in the same directory as the PHP class.

I have class Test inside Test.php and I want to use it from subfolder/index.php. Note that class Test then uses Base/Test from Base/Test.php, so using require() is not an option here as Base/Test just goes on to use even more classes generated by composer.

Traditionally, I'm supposed to do the following:

<?php
   use Test;
?>

but since I have Test in the parent folder, I cannot do that, and obviously

<?php
   use ../Test;
?>

doesn't work.

My folder structure:

My Project
|-- Base
|   `-- Test.php <-- File referenced by `Test` class
|-- subfolder
|   `-- index.php <-- File I want to use `Test` from
`-- Test.php <-- File containing `Test` class

The Actual Code: subfolder/index.php:

<?php 
use \Test;
    require __DIR__ . '/../vendor/autoload.php';
    $test = new Test();
?>

Test.php:

<?php
use Base\Test as BaseTest;

class Test extends BaseTest
{

}

回答1:

Test is a namespace and has literally nothing to do with folder structure. Namespaces have a folder-like structure, but you cannot use relative paths.

PSR-4 autoloaders, such as what most Composer packages use these days, map their namespaces in a way that very closely matches the folder structure, but they are still entirely separate concepts.

If you have declared a namespace in a file all subsequent names are considered to be relative to that path. eg:

namespace Foo;

class Bar {}; // \Foo\Bar

If you want to use something outside of the current namespace you need to declare the full path, beginning with \ which signifies the root namespace. eg:

namespace Foo;
use \Test

class Bar { // \Foo\Bar
  public function test() {
    $test = new Test();
    $dbh = new \PDO();
  }
}

来源：https://stackoverflow.com/questions/32790127/php-use-class-in-parent-folder

标签

php

namespaces

composer-php

propel