function hook_ctools_plugin_directory

Tells CTools where to find module-defined plugins.

This hook is used to inform the CTools plugin system about the location of a directory that should be searched for files containing plugins of a particular type. CTools invokes this same hook for all plugins, using the two passed parameters to indicate the specific type of plugin for which it is searching.

The $plugin_type parameter is self-explanatory - it is the string name of the plugin type (e.g., Panels' 'layouts' or 'styles'). The $owner parameter is necessary because CTools internally namespaces plugins by the module that owns them. This is an extension of Drupal best practices on avoiding global namespace pollution by prepending your module name to all its functions. Consequently, it is possible for two different modules to create a plugin type with exactly the same name and have them operate in harmony. In fact, this system renders it impossible for modules to encroach on other modules' plugin namespaces.

Given this namespacing, it is important that implementations of this hook check BOTH the $owner and $plugin_type parameters before returning a path. If your module does not implement plugins for the requested module/plugin combination, it is safe to return nothing at all (or NULL). As a convenience, it is also safe to return a path that does not exist for plugins your module does not implement - see form 2 for a use case.

Note that modules implementing a plugin also must implement this hook to instruct CTools as to the location of the plugins. See form 3 for a use case.

The conventional structure to return is "plugins/$plugin_type" - that is, a 'plugins' subdirectory in your main module directory, with individual directories contained therein named for the plugin type they contain.

Parameters

string $owner: The system name of the module owning the plugin type for which a base directory location is being requested.

string $plugin_type: The name of the plugin type for which a base directory is being requested.

Return value

string The path where CTools' plugin system should search for plugin files, relative to your module's root. Omit leading and trailing slashes.

File

./ctools.api.php, line 75

Code

function hook_ctools_plugin_directory($owner, $plugin_type) {
    // Form 1 - for a module implementing only the 'content_types' plugin owned
    // by CTools, this would cause the plugin system to search the
    // <moduleroot>/plugins/content_types directory for .inc plugin files.
    if ($owner == 'ctools' && $plugin_type == 'content_types') {
        return 'plugins/content_types';
    }
    // Form 2 - if your module implements only Panels plugins, and has 'layouts'
    // and 'styles' plugins but no 'cache' or 'display_renderers', it is OK to be
    // lazy and return a directory for a plugin you don't actually implement (so
    // long as that directory doesn't exist). This lets you avoid ugly in_array()
    // logic in your conditional, and also makes it easy to add plugins of those
    // types later without having to change this hook implementation.
    if ($owner == 'panels') {
        return "plugins/{$plugin_type}";
    }
    // Form 3 - CTools makes no assumptions about where your plugins are located,
    // so you still have to implement this hook even for plugins created by your
    // own module.
    if ($owner == 'mymodule') {
        // Yes, this is exactly like Form 2 - just a different reasoning for it.
        return "plugins/{$plugin_type}";
    }
    // Finally, if nothing matches, it's safe to return nothing at all (== NULL).
}