相对名称空间和call_user_func() [英] Relative namespaces and call_user_func()

问题描述

代码胜于雄辩:

namespaces.php :

<?php

namespace foo;

use foo\models;

class factory
{
    public static function create($name)
    {
        /*
         * Note 1: FQN works!
         * return call_user_func("\\foo\\models\\$name::getInstance");
         *
         * Note 2: direct instantiation of relative namespaces works!
         * return models\test::getInstance();
         */

        // Dynamic instantiation of relative namespaces fails: class 'models\test' not found
        return call_user_func("models\\$name::getInstance");
    }
}

namespace foo\models;

class test
{
    public static $instance;

    public static function getInstance()
    {
        if (!self::$instance) {
            self::$instance = new self;
        }

        return self::$instance;
    }

    public function __construct()
    {
        var_dump($this);
    }
}

namespace_test.php :

<?php

require_once 'namespaces.php';

foo\factory::create('test');

如前所述，如果我在call_user_func()中使用全限定名，它会按预期工作，但如果使用相对名称空间，则表示找不到该类.但是直接实例化是可行的.我是否故意遗漏了某些东西或它的奇怪?

As commented, if I use the full-qualified name inside call_user_func() it works as expected, but if I use relative namespaces it says the class was not found – but direct instantiations works. Am I missing something or its weird by design?

推荐答案

您必须在回调中使用完全限定的类名.

You have to use the fully qualified classname in callbacks.

请参见示例#3 call_user_func()使用名称空间名称

See Example #3 call_user_func() using namespace name

<?php

namespace Foobar;

class Foo {
    static public function test() {
        print "Hello world!\n";
    }
}

call_user_func(__NAMESPACE__ .'\Foo::test'); // As of PHP 5.3.0
call_user_func(array(__NAMESPACE__ .'\Foo', 'test')); // As of PHP 5.3.0

我相信这是因为call_user_func是来自全局范围的函数，同时也从全局范围执行回调.无论如何，请参见第一句话.

I believe this is because call_user_func is a function from the global scope, executing the callback from the global scope as well. In any case, see first sentence.

另请参见上面的说明示例#2动态访问命名空间元素，其中指出

Also see the note aboveExample #2 Dynamically accessing namespaced elements which states

必须使用标准名称(带有名称空间前缀的类名称).

One must use the fully qualified name (class name with namespace prefix).

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