我试图在激活第一个插件的同时自动激活第二个插件。

register_activation_hook(__FILE__, \'example_activation\' );
function example_activation() {
        include_once(ABSPATH .\'/wp-admin/includes/plugin.php\');
        activate_plugin(\'hello.php\');
}

它在register\\u activation\\u hook内不工作。。如果我直接使用它，它就会起作用，比如：

include_once(ABSPATH .\'/wp-admin/includes/plugin.php\');
activate_plugin(\'hello.php\');

我怎样才能修复它？谢谢你的帮助

解决方案：

我现在自己用这个：

// When this plugin activate, activate another plugin too.
register_activation_hook(__FILE__, function(){
    $dependent = \'hello.php\';
    if( is_plugin_inactive($dependent) ){
        add_action(\'update_option_active_plugins\', function($dependent){
            /* for some reason, 
            activate_plugin($dependent); 
               is not working */
            activate_plugin(\'hello.php\');
        });
    }
}); 

// When this plugin deactivate, deactivate another plugin too.
register_deactivation_hook(__FILE__, function(){
    $dependent = \'hello.php\';
    if( is_plugin_active($dependent) ){
        add_action(\'update_option_active_plugins\', function($dependent){
            deactivate_plugins(\'hello.php\');
        });
    }
}); 

//This goes inside Plugin A.
//When A is activated. activate B.
register_activation_hook(__FILE__,\'my_plugin_A_activate\'); 
function my_plugin_A_activate(){
    $dependent = \'B/B.php\';
    if( is_plugin_inactive($dependent) ){
         add_action(\'update_option_active_plugins\', \'my_activate_dependent_B\');
    }
}

function my_activate_dependent_B(){
    $dependent = \'B/B.php\';
    activate_plugin($dependent);
}