Analysis of WordPress plugin implementation process

1, first of all, I now write a pugins folder under the plugin

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PHP Code:

<?php　
/*
Plugin Name: test
Plugin URI: [url=http://wordpress.org/]http://wordpress.org/[/url]#
Description: 我测试用的
Author: lw(fantasy)
Version: 0.1
Author URI: [url=http://www.xxx.com/]http://www.xxx.com/[/url]　
*/　
$test = "<div id='my_test'>这是我的第一个插件!</div>";
function output(){　
　　global $test;
　　echo $test;
}
add_action('wp_footer','output');
?>

And then enable it in the background.

2, WP implementation is loaded in the "wp-settings.php", and in this file, you can find the following plug-in-related code snippets:

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PHP Code:

if ( get_option('active_plugins') ) {
$current_plugins = get_option('active_plugins');
dump($current_plugins);
if ( is_array($current_plugins) ) {
　foreach ($current_plugins as $plugin) {
　 if ( '' != $plugin && 0 == validate_file($plugin) && file_exists(WP_PLUGIN_DIR . '/' . $plugin) )
　　include_once(WP_PLUGIN_DIR . '/' . $plugin);
　}
}}

I dump a bit of $current_plugins and get

Array
(
　　[0] => Fanfou-Daily/Fanfou-Daily.php
　　[1] => mulberrykit.php
　　[2] => test.php
)

I can see that the test.php plugin I wrote has been included.

3, in the theme template in the footer.php inside will perform a function

<?php Wp_footer ();?>

And this wp_footer inside and out.

Do_action (' Wp_footer ');