Filter

• Register a filter
  • Priority and accepted arguments
  • Function, closure and class
• Run a filter
• Check filter existence
• Remove a filter
• Retrieve filter callback

Register a filter

The Filter class is a wrapper of the WordPress filter/hook API. To register a filter, simply use the add() method like so:

Filter::add('wp_terms_checklist_args', 'ClassName@checklist');

The method allows you to register your filter function/method using the same syntax as a route's controller. Specify your full class name followed by the @ symbol and the method.

The code above is calling the checklist method of the ClassName class:

class ClassName
{
    public function checklist()
    {
        // Call by the wp_terms_checklist_args filter.
        // Code..
    }
}

Note that you must provide the full class name with its namespace, as for now, the Hook API do not handle a default namespace property.

You can also omit the method name. By default, the API is looking for a class method with the same name as the filter. So if your filter is wp_terms_checklist_args, the class will look after the wp_terms_checklist_args method:

Filter::add('wp_terms_checklist_args', 'ClassName');

// ClassName
class ClassName
{
    public function wp_terms_checklist_args()
    {
        // Code...
    }
}

Note: make sure to always set your method as public otherwise WordPress can't use it.

Priority and accepted arguments

You can specify the priority and the number of arguments your filter method/function will receive using the third and fourth parameters respectively. By default, the priority is set to 10 and the number of arguments to 3.

Here is an example on how to set a priority and a number of accepted arguments:

Filter::add('get_attached_file', 'AwesomeClass', 5, 2);

Function, closure and class

The Filter::add() method also works like the default WordPress function add_filter().

You can pass it a function name or a closure like so:

// Using a function
function callback()
{
    // Code...
}

Filter::add('update_attached_file', 'callback');

// Using a closure
Filter::add('register_post_type_args', function()
{
    // Code...
});

The add() method also supports this default syntax in order to use a class:

// Use it inside a class
Filter::add('do_mu_upgrade', [$this, 'upgrade']);

// With an instance.
$class = new ClassName();
Filter::add('customize_panel_active', [$class, 'panel']);

Run a filter

In order to trigger a filter, use the run() method. The run() method is equivalent to WordPress core function apply_filters and apply_filters_ref_array(). Here is an example:

use Themosis\Facades\Filter;

Filter::run('custom', $args);

The first argument is the name of your filter hook. The second parameter is optional and let you pass data that can be accessed into registered callback.

Check filter existence

You can verify the existence of a filter by using the exists() method. Current implementation check the existence of any filters registered through the Filter class.

use Themosis\Facades\Filter;

if (Filter::exists('custom')) {
    // Run some code...
}

Remove a filter

In order to remove a filter, use the remove() method like so:

// Using default priority.
$filter = Filter::add('wp_editor_settings', 'SomeClass@method');
$filter->remove('wp_editor_settings');

// Using custom priority - The priority must be defined as well on remove if different than 10.
$filter = Filter::add('the_editor_content', 'SomeClass@method', 5);
$action->remove('the_editor_content', 5);

Retrieve filter callback

The filter class also provides a public method to help you retrieve the associated callback for your registered filter. Use the getCallback() method:

$filter = Filter::add('https_ssl_verify', 'SomeClass@method');
$cb = $filter->getCallback('init');