Phalcon automatically loads (PHP automatically loads), phalcon loads php

automatically loads (phalconLoader)

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1. PHP file introduction

Through the include() or require() function, the contents of a file can be inserted into the file before the PHP program is executed.

<p>区别：<span>处理错误的方式不同</span>。<strong>include() 函数</strong>会生成一个<span><strong>警告</strong></span>（但是脚本会继续执行），而 <strong>require()</strong> 函数会生成一个<span><strong>致命错误</strong></span>（fatal error）（在错误发生后脚本会停止执行）</p>

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　* Because the script will not continue execution if the file does not exist or is renamed, we recommend using require() instead of include().

2. PHP class automatic loading

Reference articles: PHP manual and PHP’s class automatic loading mechanism

Before PHP5, the loading of each PHP framework implementation class generally required a traversal of the directory according to a certain agreement to automatically load file classes or functions that meet the agreed conditions. Therefore, the use of classes before php5 was not as frequent as it is now.

After php5, when loading a php class, if the folder where the class is located is not included or the class name is wrong, the Zend engine will automatically call the __autoload function . The __autoload function needs to be implemented by the user.

After version php5.1.2, you can use the spl_autoload_register function to customize the loading processing function. When this function is not called, spl's custom spl_autoload function will be used by default.

1. PHP automatic loading __autoload

<span>function</span> __autoload(<span>$className</span><span>) {
    </span><span>$file</span> = <span>$className</span> . '.php'<span>;
    </span><span>if</span> (<span>is_file</span>(<span>$file</span><span>)) {
        </span><span>require</span>(<span>$file</span><span>);
    }</span><span>else</span><span>{
        </span><span>echo</span> 'no this ' . <span>$className</span> . ' class file'<span>;
    }
}
</span><span>$demo</span> = <span>new</span> Demo();

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In fact, we can see that __autoload needs to do at least three things ("Three steps"), they are:

In the first and second steps, we must agree on the mapping method of the class name and the file. Only in this way can we find the corresponding file based on the class name. , to achieve loading.

Therefore, the most important thing in __autoload automatic loading is the corresponding relationship between the specified class name and the file in which it is located . When there are a large number of classes that need to be included, we only need to establish the corresponding rules , and then map the class names to their corresponding files to achieve Lazy loading is done.

<p><strong>Tip：</strong>spl_autoload_register() 提供了一种更加灵活的方式来实现类的自动加载。因此，不再建议使用 __autoload() 函数，在以后的版本中它可能被弃用。</p>

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2. PHP automatic loading spl_autoload_register

Introduction: If many other class libraries are used in a PHP system implementation, these class libraries may be developed by different engineers, so the mapping rules between class names and the files where they are located are different. At this time, if you want to implement automatic loading of the class library, you must implement all mapping rules in the __autoload function. This will cause __autoload to be very complicated or even impossible to implement. At the same time, it will also make the __autoload function very bloated. It will have a great negative impact on future system maintenance and performance. (Disadvantages of __autoload)

spl_autoload_register:

Register the given function as an implementation of __autoload. To put it simply, the function is registered in the __autoload function stack of SPL and the system default __autload() function is removed.

<span>function</span> __autoload(<span>$className</span><span>) {  
    </span><span>echo</span> 'autload class:', <span>$className</span>, '<br />'<span>;  
}  
</span><span>function</span> classLoader(<span>$className</span><span>) {  
    </span><span>echo</span> 'SPL load class:', <span>$className</span>, '<br />'<span>;  
}  
spl_autoload_register(</span>'classLoader'<span>);  
</span><span>new</span> Test();<span>//</span><span>结果：SPL load class:Test </span>

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<p><strong>Tip：</strong></p>

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Function Description

<pre class="code"><span><strong><code>bool spl_autoload_register ([ callable $autoload_function [, bool $throw = true [, bool $prepend = false ]]] )
</code></strong></span>

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autoload_function [optional] Function added to the autoload stack. The default is spl_autoload().
- You can also call the spl_autoload_register() function to register a callback function instead of providing a string name for the function. For example, if you provide an array such as array('class','method'), you can use the method of an object .
throw [optional] whether to throw an exception when registration cannot be successful
prepend [Optional] Whether to add this function to the head of the queue instead of the tail of the queue.

<p><strong>备注：</strong>SPL自动加载功能是由spl_autoload() ,spl_autoload_register(), spl_autoload_functions() ,spl_autoload_extensions()和spl_autoload_call()函数提供的。</p>

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3. Phalcon’s class automatic loading

PhalconLoader Universal Class Loader is intended to help the project automatically load classes in the project according to the protocol (This component helps to load your project classes automatically based on some conventions). Phalcon supports four class loading methods, the order of which is registering class name, registering namespace, registering prefix and registering folder.

Phalcon’s default file suffix is php, of course you can also configure it yourself (setExtensions()).

1. Register class name

<?<span>php
</span><span>$loader</span> = <span>new</span><span> \Phalcon\Loader();
</span><span>$loader</span>-><span>registerClasses(
    </span><span>array</span><span>(
        </span>"Some"         => "library/OtherComponent/Other/Some.php",
        "Example\Base" => "vendor/example/adapters/Example/BaseClass.php",<span>
    )
);
</span><span>$loader</span>-><span>register();    
</span><span>//</span><span> i.e. library/OtherComponent/Other/Some.php</span>
<span>$some</span> = <span>new</span> Some();

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<p>具体实现：</p>

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2. Register namespace

<?<span>php
</span><span>$loader</span> = <span>new</span><span> \Phalcon\Loader();
</span><span>$loader</span>-><span>registerNamespaces(
    </span><span>array</span><span>(
       </span>"Example\Base"    => "vendor/example/base/",
       "Example\Adapter" => "vendor/example/adapter/",
       "Example"         => "vendor/example/",<span>
    )
);
</span><span>$loader</span>-><span>register();
</span><span>//</span><span> vendor/example/adapter/Some.php</span>
<span>$some</span> = <span>new</span> Example\Adapter\Some();

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When using namespaces or external libraries to organize code, you can register the namespace to automatically load the libraries it contains.

对于命名空间对应的路径，要其末尾加一个斜杠。
<p>具体实现：</p>

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3. Registration prefix

<?<span>php
</span><span>$loader</span> = <span>new</span><span> \Phalcon\Loader();
</span><span>$loader</span>-><span>registerPrefixes(
    </span><span>array</span><span>(
       </span>"Example_Base"     => "vendor/example/base/",
       "Example_Adapter"  => "vendor/example/adapter/",
       "Example_"         => "vendor/example/",<span>
    )
);    
</span><span>$loader</span>-><span>register();    
</span><span>//</span><span> vendor/example/adapter/Some.php</span>
<span>$some</span> = <span>new</span> Example_Adapter_Some();

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Similar to namespaces, phalcon will no longer support prefixes starting from 2.1.0.

<p>具体实现：</p>

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4. Register folder

<?<span>php
</span><span>$loader</span> = <span>new</span><span> \Phalcon\Loader();    
</span><span>$loader</span>-><span>registerDirs(
    </span><span>array</span><span>(
        </span>"library/MyComponent/",
        "library/OtherComponent/Other/",
        "vendor/example/adapters/",
        "vendor/example/"<span>
    )
);    
</span><span>$loader</span>-><span>register();    
</span><span>//</span><span> i.e. library/OtherComponent/Other/Some.php</span>
<span>$some</span> = <span>new</span> Some();

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Can automatically load class files in the registration directory. However, this method is not recommended in terms of performance, because Phalcon will look for a large number of files with the same class name in each folder. When using the registration directory to automatically load, pay attention to the relevance of the registration directory, that is, put the important directories in front.

<p>具体实现：</p>

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5. 修改当前策略(Modifying current strategies)

即为当前自动加载数据添加额外的值。

<?<span>php
</span><span>//</span><span> Adding more directories</span>
<span>$loader</span>-><span>registerDirs(
    </span><span>array</span><span>(
        </span>"../app/library/",
        "../app/plugins/"<span>
    )</span>,
    <span>true</span><span>
);</span>

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注册时添加第二个参数值true，使其与原数组合并。

6. 安全层（Security Layer）

没有进行任何安全检查的自动加载器，如下：

<?<span>php
</span><span>//</span><span>Basic autoloader</span>
spl_autoload_register(<span>function</span>(<span>$className</span><span>) {
    </span><span>if</span> (<span>file_exists</span>(<span>$className</span> . '.php'<span>)) {
        </span><span>require</span> <span>$className</span> . '.php'<span>;
    }
});</span>

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假如我们没有进行任何安全检查时，如果误启了自动加载器，那么恶意准备的字符串就回作为参数访问程序中的重要文件。

<?<span>php

</span><span>//</span><span>This variable is not filtered and comes from an insecure source</span>
<span>$className</span> = '../processes/important-process'<span>;

</span><span>//</span><span>Check if the class exists triggering the auto-loader</span>
<span>if</span> (<span>class_exists</span>(<span>$className</span><span>)) {
    </span><span>//</span><span>...</span>
}

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Phalcon的做法是删除任何无用的字符串，减少被攻击的可能性。

7. 自动加载事件

在下面的例子中,而不必使用类加载器,使我们获得调试信息的流程操作:

<?<span>php
</span><span>$eventsManager</span> = <span>new</span><span> \Phalcon\Events\Manager();
</span><span>$loader</span> = <span>new</span><span> \Phalcon\Loader();
</span><span>$loader</span>->registerNamespaces(<span>array</span><span>(
       </span>'Example\\Base' => 'vendor/example/base/',
       'Example\\Adapter' => 'vendor/example/adapter/',
       'Example' => 'vendor/example/'<span>
));
</span><span>//</span><span>Listen all the loader events</span>
<span>$eventsManager</span>->attach('loader', <span>function</span>(<span>$event</span>, <span>$loader</span><span>) {
    </span><span>if</span> (<span>$event</span>-><span>getType</span>() == 'beforeCheckPath'<span>) {
        </span><span>echo</span> <span>$loader</span>-><span>getCheckedPath();
    }
});
</span><span>$loader</span>->setEventsManager(<span>$eventsManager</span><span>);
</span><span>$loader</span>->register();

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Phalcon自动加载支持以下事件: