WordPress 插件继续文档：面向对象编程 II

在本系列的这一点上，我们已准备好通过记录我们的文件、类、函数、变量等来完善我们的插件。

虽然这是我们实际上必须完成插件的最后一步，但这并不是该系列的最后一篇文章，因为我们将继续研究面向对象编程中的一些高级主题。

但在此之前，让我们将我们在上一篇文章中学到的所有内容付诸实践，将我们的插件升级到 1.0 版本。

当然，与之前的所有文章一样，我建议您及时了解我们迄今为止介绍的所有内容，这样您不仅可以完全了解我们所做的工作在上一篇文章中，但我们实际上是如何达到本文讨论的最后一点的。

1. 简介
2. 课程
3. 类型
4. 控制结构：条件语句
5. 控制结构：循环
6. 函数和属性
7. 范围
8. 构建插件 I
9. 构建插件 II
10. 记录插件 I

了解和审查了所有这些内容后，让我们开始记录每个文件。

记录插件

我们可以通过多种不同的方式来记录这个插件：

• 我们可以首先记录所有文件头，然后我们可以回来记录类，然后我们可以回来记录变量，然后我们可以记录函数。
• 我们可以一次记录每个文件，并对每个文件中包含的所有内容进行简短的讨论。

显然，该选项将为每个部分生成更多文档，但应该会导致一篇不那么乏味的文章，并且更容易理解整个插件的控制流程。

为此，我们将逐个文件地研究该插件，为我们拥有的每段代码引入文档，然后我们将讨论代码后面的任何感兴趣的点。

最后，我们将确保在文章末尾引用该插件的最终版本。话虽如此，让我们开始吧。

单个帖子元管理器

回想一下，启动插件的主文件是位于插件目录根目录中的 single-post-meta-manager.php 文件。

以下是该文件的完整文档版本。仔细阅读每条评论，不仅要注意其遵循的格式，还要注意其提供的内容。

<?php
/**
 * The file responsible for starting the Single Post Meta Manager plugin
 *
 * The Single Post Meta Manager is a plugin that displays the post meta data
 * associated with a given post. This particular file is responsible for
 * including the necessary dependencies and starting the plugin.
 *
 * @package SPPM
 *
 * @wordpress-plugin
 * Plugin Name:       Single Post Meta Manager
 * Plugin URI:        https://github.com/tommcfarlin/post-meta-manager
 * Description:       Single Post Meta Manager displays the post meta data associated with a given post.
 * Version:           1.0.0
 * Author:            Tom McFarlin
 * Author URI:        http://tommcfarlin.com
 * Text Domain:       single-post-meta-manager-locale
 * License:           GPL-2.0+
 * License URI:       http://www.gnu.org/licenses/gpl-2.0.txt
 * Domain Path:       /languages
 */

// If this file is called directly, then about execution.
if ( ! defined( 'WPINC' ) ) {
    die;
}

/**
 * Include the core class responsible for loading all necessary components of the plugin.
 */
require_once plugin_dir_path( __FILE__ ) . 'includes/class-single-post-meta-manager.php';

/**
 * Instantiates the Single Post Meta Manager class and then
 * calls its run method officially starting up the plugin.
 */
function run_single_post_meta_manager() {

	$spmm = new Single_Post_Meta_Manager();
	$spmm->run();

}

// Call the above function to begin execution of the plugin.
run_single_post_meta_manager();

在上面的代码中，请注意，我们已经根据上一篇文章中概述的约定定义了文件头。我们还维护了所需的插件标头标签，以便 WordPress 正确读取它们。

请注意，在本例中，我们已将它们包含在自定义 @wordpress-plugin 标记下。这不是必需的，但有助于将文件头注释与所需的插件注释分开。

最后，请注意，我们已将此插件的版本提升至 1.0，并且我们还为该插件指定了 @package 值="inline">SPMM 缺少Single Post Meta Manager。我们将在整个插件中使用它。

包含目录

接下来，让我们将注意力转向包含目录中的所有文件。

由于在管理目录中的任何内容之前都需要这些文件，因此单独查看这些文件中的每一个是有意义的，然后用管理目录中的其余文件来完善我们的讨论。

单个帖子元管理器

<?php

/**
 * The Single Post Meta Manager is the core plugin responsible for including and
 * instantiating all of the code that composes the plugin
 *
 * @package SPMM
 */

/**
 * The Single Post Meta Manager is the core plugin responsible for including and
 * instantiating all of the code that composes the plugin.
 *
 * The Single Post Meta Manager includes an instance to the Single Post Manager
 * Loader which is responsible for coordinating the hooks that exist within the
 * plugin.
 *
 * It also maintains a reference to the plugin slug which can be used in
 * internationalization, and a reference to the current version of the plugin
 * so that we can easily update the version in a single place to provide
 * cache busting functionality when including scripts and styles.
 *
 * @since    1.0.0
 */
class Single_Post_Meta_Manager {

    /**
	 * A reference to the loader class that coordinates the hooks and callbacks
	 * throughout the plugin.
	 *
	 * @access protected
	 * @var    Single_Post_Meta_Manager_Loader   $loader    Manages hooks between the WordPress hooks and the callback functions.
	 */
	protected $loader;

	/**
	 * Represents the slug of hte plugin that can be used throughout the plugin
	 * for internationalization and other purposes.
	 *
	 * @access protected
	 * @var    string   $plugin_slug    The single, hyphenated string used to identify this plugin.
	 */
	protected $plugin_slug;

	/**
	 * Maintains the current version of the plugin so that we can use it throughout
	 * the plugin.
	 *
	 * @access protected
	 * @var    string   $version    The current version of the plugin.
	 */
	protected $version;

	/**
	 * Instantiates the plugin by setting up the core properties and loading
	 * all necessary dependencies and defining the hooks.
	 *
	 * The constructor will define both the plugin slug and the verison
	 * attributes, but will also use internal functions to import all the
	 * plugin dependencies, and will leverage the Single_Post_Meta_Loader for
	 * registering the hooks and the callback functions used throughout the
	 * plugin.
	 */
	public function __construct() {

		$this->plugin_slug = 'single-post-meta-manager-slug';
		$this->version = '1.0.0';

		$this->load_dependencies();
		$this->define_admin_hooks();

	}



	/**
	 * Imports the Single Post Meta administration classes, and the Single Post Meta Loader.
	 *
	 * The Single Post Meta Manager administration class defines all unique functionality for
	 * introducing custom functionality into the WordPress dashboard.
	 *
	 * The Single Post Meta Manager Loader is the class that will coordinate the hooks and callbacks
	 * from WordPress and the plugin. This function instantiates and sets the reference to the
	 * $loader class property.
	 *
	 * @access    private
	 */
	private function load_dependencies() {

		require_once plugin_dir_path( dirname( __FILE__ ) ) . 'admin/class-single-post-meta-manager-admin.php';

		require_once plugin_dir_path( __FILE__ ) . 'class-single-post-meta-manager-loader.php';
		$this->loader = new Single_Post_Meta_Manager_Loader();

	}

	/**
	 * Defines the hooks and callback functions that are used for setting up the plugin stylesheets
	 * and the plugin's meta box.
	 *
	 * This function relies on the Single Post Meta Manager Admin class and the Single Post Meta Manager
	 * Loader class property.
	 *
	 * @access    private
	 */
	private function define_admin_hooks() {

		$admin = new Single_Post_Meta_Manager_Admin( $this->get_version() );
		$this->loader->add_action( 'admin_enqueue_scripts', $admin, 'enqueue_styles' );
		$this->loader->add_action( 'add_meta_boxes', $admin, 'add_meta_box' );

	}

	/**
	 * Sets this class into motion.
	 *
	 * Executes the plugin by calling the run method of the loader class which will
	 * register all of the hooks and callback functions used throughout the plugin
	 * with WordPress.
	 */
	public function run() {
		$this->loader->run();
	}

	/**
	 * Returns the current version of the plugin to the caller.
	 *
	 * @return    string    $this->version    The current version of the plugin.
	 */
	public function get_version() {
		return $this->version;
	}

}

显然，这个特定文件中引入了很多新评论；但是，每个类属性、构造函数和内部函数的作用应该是非常不言自明的。

除了如何通过插件协调信息之外，需要注意的关键是我们如何遵守上一篇文章中定义的标准。

但请注意，如果文档中的某些标签和/或功能在不相关时不使用，我们就冒昧地使用它们。我们将在本文的其余部分中继续这样做。

单个帖子元管理器加载器

<?php

/**
 * The Single Post Meta Manager Loader is a class that is responsible for
 * coordinating all actions and filters used throughout the plugin
 *
 * @package    SPMM
 */

/**
 * The Single Post Meta Manager Loader is a class that is responsible for
 * coordinating all actions and filters used throughout the plugin.
 *
 * This class maintains two internal collections - one for actions, one for
 * hooks - each of which are coordinated through external classes that
 * register the various hooks through this class.
 *
 * @since    1.0.0
 */
class Single_Post_Meta_Manager_Loader {

    /**
	 * A reference to the collection of actions used throughout the plugin.
	 *
	 * @access protected
	 * @var    array    $actions    The array of actions that are defined throughout the plugin.
	 */
	protected $actions;

	/**
	 * A reference to the collection of filters used throughout the plugin.
	 *
	 * @access protected
	 * @var    array    $actions    The array of filters that are defined throughout the plugin.
	 */
	protected $filters;

	/**
	 * Instantiates the plugin by setting up the data structures that will
	 * be used to maintain the actions and the filters.
	 */
	public function __construct() {

		$this->actions = array();
		$this->filters = array();

	}

	/**
	 * Registers the actions with WordPress and the respective objects and
	 * their methods.
	 *
	 * @param  string    $hook        The name of the WordPress hook to which we're registering a callback.
	 * @param  object    $component   The object that contains the method to be called when the hook is fired.
	 * @param  string    $callback    The function that resides on the specified component.
	 */
	public function add_action( $hook, $component, $callback ) {
		$this->actions = $this->add( $this->actions, $hook, $component, $callback );
	}

	/**
	 * Registers the filters with WordPress and the respective objects and
	 * their methods.
	 *
	 * @param  string    $hook        The name of the WordPress hook to which we're registering a callback.
	 * @param  object    $component   The object that contains the method to be called when the hook is fired.
	 * @param  string    $callback    The function that resides on the specified component.
	 */
	public function add_filter( $hook, $component, $callback ) {
		$this->filters = $this->add( $this->filters, $hook, $component, $callback );
	}

	/**
	 * Registers the filters with WordPress and the respective objects and
	 * their methods.
	 *
	 * @access private
	 *
	 * @param  array     $hooks       The collection of existing hooks to add to the collection of hooks.
	 * @param  string    $hook        The name of the WordPress hook to which we're registering a callback.
	 * @param  object    $component   The object that contains the method to be called when the hook is fired.
	 * @param  string    $callback    The function that resides on the specified component.
	 *
	 * @return array                  The collection of hooks that are registered with WordPress via this class.
	 */
	private function add( $hooks, $hook, $component, $callback ) {

		$hooks[] = array(
			'hook'      => $hook,
			'component' => $component,
			'callback'  => $callback
		);

		return $hooks;

	}

	/**
	 * Registers all of the defined filters and actions with WordPress.
	 */
	public function run() {

		 foreach ( $this->filters as $hook ) {
			 add_filter( $hook['hook'], array( $hook['component'], $hook['callback'] ) );
		 }

		 foreach ( $this->actions as $hook ) {
			 add_action( $hook['hook'], array( $hook['component'], $hook['callback'] ) );
		 }

	}

}

请注意，此类或多或少是插件的核心组件，因为它协调整个插件中使用的所有操作和过滤器。该插件集中了整个插件中使用的钩子的所有注册和协调。

最后，当调用 run 时，所有挂钩都会向 WordPress 注册，因此当插件启动时，它将调用每个注册的操作和过滤器。

admin 目录

此时，我们准备将注意力转向位于插件管理目录中的文件。

虽然该文件由几个 PHP 文件组成，但它还包含一个 CSS 文件。出于本文的目的，我们不会记录 CSS 文件；我们将编写 CSS 文件。但是，WordPress Codex确实为此定义了文档。

现在，让我们继续记录 admin 目录中存在的类和文件。

单个帖子元管理器管理员

Single Post Meta Manager Admin 类具有单一职责：定义为仪表板呈现元框及其样式的功能。

<?php

/**
 * The Single Post Meta Manager Admin defines all functionality for the dashboard
 * of the plugin
 *
 * @package SPMM
 */

/**
 * The Single Post Meta Manager Admin defines all functionality for the dashboard
 * of the plugin.
 *
 * This class defines the meta box used to display the post meta data and registers
 * the style sheet responsible for styling the content of the meta box.
 *
 * @since    1.0.0
 */
class Single_Post_Meta_Manager_Admin {

    /**
	 * A reference to the version of the plugin that is passed to this class from the caller.
	 *
	 * @access private
	 * @var    string    $version    The current version of the plugin.
	 */
	private $version;

	/**
	 * Initializes this class and stores the current version of this plugin.
	 *
	 * @param    string    $version    The current version of this plugin.
	 */
	public function __construct( $version ) {
		$this->version = $version;
	}

	/**
	 * Enqueues the style sheet responsible for styling the contents of this
	 * meta box.
	 */
	public function enqueue_styles() {

		wp_enqueue_style(
			'single-post-meta-manager-admin',
			plugin_dir_url( __FILE__ ) . 'css/single-post-meta-manager-admin.css',
			array(),
			$this->version,
			FALSE
		);

	}

	/**
	 * Registers the meta box that will be used to display all of the post meta data
	 * associated with the current post.
	 */
	public function add_meta_box() {

		add_meta_box(
			'single-post-meta-manager-admin',
			'Single Post Meta Manager',
			array( $this, 'render_meta_box' ),
			'post',
			'normal',
			'core'
		);

	}

	/**
	 * Requires the file that is used to display the user interface of the post meta box.
	 */
	public function render_meta_box() {
		require_once plugin_dir_path( __FILE__ ) . 'partials/single-post-meta-manager.php';
	}

}

请注意，上面的类只有很少的功能细节。主要是，该类维护对插件版本的引用、用于设置元框样式的样式表以及实际渲染元框所需的函数。

回想一下，所有这些都是在核心插件文件和加载器中设置的。这有助于解耦插件中存在的逻辑，以便每个类都可以专注于其主要目的。

当然，插件的最后一部分依赖于包含显示元框所需标记的实际部分文件。

单个帖子元管理器部分

<?php
/**
 * Displays the user interface for the Single Post Meta Manager meta box.
 *
 * This is a partial template that is included by the Single Post Meta Manager
 * Admin class that is used to display all of the information that is related
 * to the post meta data for the given post.
 *
 * @package    SPMM
 */
?>
<div id="single-post-meta-manager">

    <?php $post_meta = get_post_meta( get_the_ID() ); ?>
	<table id="single-post-meta-manager-data">
	<?php foreach ( $post_meta as $post_meta_key => $post_meta_value ) { ?>
		<tr>
			<td class="key"><?php echo $post_meta_key; ?></td>
			<td class="value"><?php print_r( $post_meta_value[0] ); ?></td>
		</tr>
	<?php } ?>
	</table>

</div><!-- #single-post-meta-manager -->

这应该是相对不言自明的；但是，为了完整起见，请注意此文件获取当前帖子 ID（通过使用 get_the_ID() 函数），读取帖子元数据，然后迭代它构建一个表显示键和值。

完成插件

至此，我们已经完成了插件的实现。从实施面向对象的编程实践，到记录代码。

您可以在 GitHub 上获取该插件的最终版本；但是，我们将在更多帖子中继续进行面向对象的讨论，以便我们可以探索一些更高级的主题，例如继承、抽象和其他主题。

同时，如果您对该插件有疑问或意见，请随时在评论中留下！

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