How do I create Widget within plugin that uses its own class?

Question

I wrote WordPress plugin and want to include 2 extra Widgets with it...

if( !class_exists('plugin_name') ) {
    class plugin_name {
            // plugin code
    }
}

// include widgets code
require_once( 'include/custom_functions.php' );

...and Widgets (according to WP codex) should be created like this within "custom_functions.php":

class My_Widget extends WP_Widget {
    // widget code
}
function sfp_register_widgets() {
    register_widget( 'My_Widget' );
}
add_action( 'widgets_init', 'sfp_register_widgets' );

I can't put "class SFP_Search extends WP_Widget" inside my plugin's class and if I place it outside, I get an error:

Class 'WP_Widget' not found in /Applications/XAMPP/...etc

Is there any other solution? Thanks!

Answer 1

There's no need to nest classes (and you can't anyway), you just create a new instance of the class. The code below would automatically call the My_Widget class to create a widget based on your existing code.

Class plugin_name {
        // Call the widget class
        public function __construct(){
             $this->widget = new My_Widget();
             $this->widget->getWidget();
        }
}

Class My_Widget extends WP_Widget(){
     public function getWidget(){
          //Do my widget stuff.
          echo "I'm a widget";
     }
}

Answer 2

if you are inside namespaced file, you should use slash in front of any global class:

class My_Widget extends \WP_Widget {
    ...
}