命名空间中的 PHP 自动加载

PHP Autoloading in Namespaces

提问by Sammaye

I have had a slight problem with autoloading in my namespace. As shown on the PHP manual here: http://us.php.net/manual/en/language.namespaces.rules.phpyou should be able to autoload namespace functions with a full qualified name e.g. \glue\common\is_email().

我的命名空间中的自动加载有一个小问题。如此处的 PHP 手册所示：http: //us.php.net/manual/en/language.namespaces.rules.php您应该能够使用完全限定名称自动加载命名空间函数，例如 \glue\common\is_email( ）。

Thing is I have a function spl_autoload_register(array($import, "load")); within the initial namespace but whenever I try and call \glue\common\is_email() from the initial namespace it will not pass that autoload function but when using new is_email() (in the context of a class) it will. I don't get it the manual says I can autoload from fully qualified names but I can't :.

事情是我有一个函数 spl_autoload_register(array($import, "load")); 在初始命名空间内，但是每当我尝试从初始命名空间调用 \glue\common\is_email() 时，它都不会传递该自动加载函数，但是当使用 new is_email() （在类的上下文中）时，它会传递。我不明白手册说我可以从完全限定名称自动加载，但我不能：。

Here's my code:

这是我的代码：

namespace glue;

require_once 'import.php';

use glue\import as import;
use glue\core\router as router;

$import = new import();

spl_autoload_register(array($import, "load"));

/** Works and echos glue\router **/
$router = new router();

/** Don't do nothing **/
$cheese = \glue\common\is_email($email);

I also tried this code as well:

我也试过这段代码：

namespace glue;

require_once 'import.php';

use glue\import as import;
use glue\core\router as router;
use glue\common;

$import = new import();

spl_autoload_register(array($import, "load"));

/** Works and echos glue\router **/
$router = new router();

/** Don't do nothing **/
$cheese = common\is_email($email);

and finally this code:

最后这个代码：

namespace glue;

require_once 'import.php';

use glue\import as import;
use glue\core\router as router;
use glue\common\is_email as F;

$import = new import();

spl_autoload_register(array($import, "load"));

/** Works and echos glue\router **/
$router = new router();

/** Don't do nothing **/
$cheese = F($email);

回答by Theodore R. Smith

Here's the only right answer.

这是唯一正确的答案。

Every namespace needs its own spl_autoload_register() function.

每个命名空间都需要自己的 spl_autoload_register() 函数。

also, spl_autoload_register() syntax changedin 5.3:

此外，spl_autoload_register() 语法在 5.3 中发生了变化：

spl_autoload_register(__NAMESPACE__ . "\className::functionName"));

The following should work:

以下应该工作：

namespace glue;

require_once 'import.php';

use glue\import as import;
use glue\core\router as router;

$import = new import();

spl_autoload_register(__NAMESPACE__ . "\$import::load"));

/** Works and echos glue\router **/
$router = new router();

/** Don't do nothing **/
$cheese = \glue\common\is_email($email);

---

---

Here is some livecode that Just works!

这是一些可以正常工作的实时代码！

in ../WebPageConsolidator.inc.php:

在 ../WebPageConsolidator.inc.php 中：

class WebPageConsolidator
{
    public function __construct() { echo "PHP 5.2 constructor.\n"; }
}

in test.php:

在 test.php 中：

<?php

namespace WebPage;

class MyAutoloader
{
    public static function load($className)
    {
        require '../' . __NAMESPACE__ . $className . '.inc.php';
    }
}

spl_autoload_register(__NAMESPACE__ . "\MyAutoloader::load");

class Consolidator extends \WebpageConsolidator
{
    public function __construct()
    {
        echo "PHP 5.3 constructor.\n";

        parent::__construct();
    }
}

// Output: 
// PHP 5.3 constructor.
// PHP 5.2 constructor.

So I know it works.

所以我知道它有效。

回答by Lukas Lukac

Use Composerto autoload your PHP Classes.

使用Composer自动加载您的 PHP 类。

Check out how to do it in my recent blog post: https://enchanterio.github.io/enterprise-level-php/2017/12/25/the-magic-behind-autoloading-php-files-using-composer.html

在我最近的博客文章中查看如何做到这一点：https: //enchanterio.github.io/enterprise-level-php/2017/12/25/the-magic-behind-autoloading-php-files-using-composer。 html

回答by Jpsy

The misconception in the question of the OP is probably that functions/methods would be subject to autoloading – which they are not. Autoloading is only triggered by referencing classes.

对 OP 问题的误解可能是函数/方法会受到自动加载的影响——而事实并非如此。自动加载仅通过引用类触发。

This being said there still remains the question about autoloading classes in namespaces:

话虽如此，仍然存在关于在命名空间中自动加载类的问题：

As of 2017 the current PHP-FIGstandard for autoloading is PSR-4 which provides the following autoloader code for namespaced classes:

截至 2017 年，当前用于自动加载的PHP-FIG标准是 PSR-4，它为命名空间类提供以下自动加载器代码：

<?php
/**
 * An example of a project-specific implementation.
 *
 * After registering this autoload function with SPL, the following line
 * would cause the function to attempt to load the \Foo\Bar\Baz\Qux class
 * from /path/to/project/src/Baz/Qux.php:
 *
 *      new \Foo\Bar\Baz\Qux;
 *
 * @param string $class The fully-qualified class name.
 * @return void
 */
spl_autoload_register(function ($class) {

    // project-specific namespace prefix
    $prefix = 'Foo\Bar\';

    // base directory for the namespace prefix
    $base_dir = __DIR__ . '/src/';

    // does the class use the namespace prefix?
    $len = strlen($prefix);
    if (strncmp($prefix, $class, $len) !== 0) {
        // no, move to the next registered autoloader
        return;
    }

    // get the relative class name
    $relative_class = substr($class, $len);

    // replace the namespace prefix with the base directory, replace namespace
    // separators with directory separators in the relative class name, append
    // with .php
    $file = $base_dir . str_replace('\', '/', $relative_class) . '.php';

    // if the file exists, require it
    if (file_exists($file)) {
        require $file;
    }
});

The full spec text can be found at PSR-4: Autoloader.

完整的规范文本可以在PSR-4: Autoloader 中找到。

The code example above (and another one to autoload from multiplenamespaces) can be found at Example Implementations of PSR-4(or GitHub: fig-standards/accepted/PSR-4-autoloader-examples.md).

上面的代码示例（以及另一个从多个命名空间自动加载的代码示例）可以在PSR-4 的示例实现（或 GitHub：fig-standards/accepted/PSR-4-autoloader-examples.md）中找到。