Testing for addon plugin activated

Question

I am creating a plugin which will also have a few addons. I am adding settings tabs for the addons, but I want to make a conditional check in the main plugin to prevent those tabs from showing if the addon plugin is not active.

There is the function is_plugin_active() which can be used easily for this check, but what if the user decides to change the folder name of the plugin? Then the check will not work correctly? Should I implement some kind of other more robust check?

Answer 1

There is the function is_plugin_active() which can be used easily for this check, but what if the user decides to change the folder name of the plugin?

Simply put, you're doing it wrong.

If you're making extensions for a plugin, then you should provide hooks in the "parent" plugin for those addons to hook into and change things. Take tabs, for instance, you could use a filter.

<?php
$tabs = apply_filters('myplugin_options_tabs', array(
    'some_tab'  => __('The Tab Label', 'your-textdomain'),
    'a_tab'     => __('Another Label', 'your-textdomain'),
));

foreach ($tabs as $tab => $label) {
   printf('<a href="#%s">%s</a>', esc_attr($tab), esc_html($label));
}

// some where further on where the tab content is supposed to display:
do_action('myplugin_tab_' . some_function_that_gets_the_current_tab() . '_display');

Doing it this way means you don't have to do any checks in your parent plugin. Add ons can simply hook in and do their thing. Much more elegant, and a lot more flexible.

That said, if you really really want to check for the existence of another plugin, the best bet is to hook into plugins_loaded and check for the existence of one of that plugin's classes, functions and/or constants.

<?php
add_action('plugins_loaded', 'wpse89926_load');
function wpse89926_load()
{
   if (class_exists('Other_Plugins_Class')) {
       // do stuff, the other plugin is in installed
   }

   if (function_exists('a_function_in_the_other_plugin')) {
       // do stuff, the other plugin is in installed
   }

   if (defined('A_CONSTANT_IN_THE_OTHER_PLUGIN')) {
       // do stuff, the other plugin is in installed
   }
}

Answer 2

chrisguitarguy's solution is the way to go ^^.

Just to add when a plugin is activated the folder/name is stored in the get_option, so using

 get_option( 'active_plugins', array());

will still store the folder/name even if they are changed. If you change the folder or plugin name on an active plugin the plugin will be de-activated, and thus require activation and storing of the correct folder/name.

Though some plugins will break if you do so, and thus not be activated so it's outside your concern.