为什么我收到PHP致命错误：未捕获错误：找不到类’MyClass’？

参见英文答案 > PHP static method call with variable class name and namespaces                                    2个
这有效：

class MyClass {
    public $prop = 'hi';
}

class Container {
    static protected $registry = [];
    public static function get($key){
        if(!array_key_exists($key, static::$registry)){
            static::$registry[$key] = new $key;
        }
        return static::$registry[$key];
    }
}

$obj = Container::get('MyClass');
echo $obj->prop;

hi

但是,当我尝试将其分解为单个文件时,我收到错误.

PHP Fatal error: Uncaught Error: Class ‘MyClass’ not found in /nstest/src/Container.php:9

这是第9行：

static::$registry[$key] = new $key;

令人抓狂的是我可以对其进行硬编码,并且它可以工作,所以我知道命名空间是正确的.

static::$registry[$key] = new MyClass;

hi

显然我不想硬编码因为我需要动态值.我也尝试过：

$key = $key::class;
static::$registry[$key] = new $key;

但这给了我这个错误：

PHP Fatal error: Dynamic class names are not allowed in compile-time ::class fetch

我不知所措. Clone these files to reproduce：

.
├── composer.json
├── main.php
├── src
│   ├── Container.php
│   └── MyClass.php
├── vendor
│   └── ...
└── works.php

不要忘记自动加载器.

composer dumpautoload

composer.json

{
    "autoload": {
        "psr-4": {
            "scratchers\\nstest\\": "src/"
        }
    }
}

main.php

require __DIR__.'/vendor/autoload.php';
use scratchers\nstest\Container;

$obj = Container::get('MyClass');
echo $obj->prop;

SRC/C++ontainer.php

namespace scratchers\nstest;

class Container {
    static protected $registry = [];
    public static function get($key){
        if(!array_key_exists($key, static::$registry)){
            static::$registry[$key] = new $key;
        }
        return static::$registry[$key];
    }
}

SRC / MyClass.php

namespace scratchers\nstest;

class MyClass {
    public $prop = 'hi';
}

解决方法:

Thanks to @tkausl,通过将完全限定名称作为变量传递,我能够绕过动态相对命名空间.

require __DIR__.'/vendor/autoload.php';
use scratchers\nstest\Container;
use scratchers\nstest\MyClass;

$obj = Container::get(MyClass::class);
echo $obj->prop;

hi

标签：php,oop,dependency-injection,namespaces,autoloader
来源： https://codeday.me/bug/20190611/1218763.html