Title: WP_Widget::_register_one
Published: April 25, 2014
Last modified: April 28, 2025

---

# WP_Widget::_register_one( int $number = -1 )

## In this article

 * [Parameters](https://developer.wordpress.org/reference/classes/wp_widget/_register_one/?output_format=md#parameters)
 * [Source](https://developer.wordpress.org/reference/classes/wp_widget/_register_one/?output_format=md#source)
 * [Related](https://developer.wordpress.org/reference/classes/wp_widget/_register_one/?output_format=md#related)
 * [Changelog](https://developer.wordpress.org/reference/classes/wp_widget/_register_one/?output_format=md#changelog)

[ Back to top](https://developer.wordpress.org/reference/classes/wp_widget/_register_one/?output_format=md#wp--skip-link--target)

Registers an instance of the widget class.

## 󠀁[Parameters](https://developer.wordpress.org/reference/classes/wp_widget/_register_one/?output_format=md#parameters)󠁿

 `$number`intoptional

The unique order number of this widget instance compared to other instances of the
same class.

Default:`-1`

## 󠀁[Source](https://developer.wordpress.org/reference/classes/wp_widget/_register_one/?output_format=md#source)󠁿

    ```php
    public function _register_one( $number = -1 ) {
    	wp_register_sidebar_widget(
    		$this->id,
    		$this->name,
    		$this->_get_display_callback(),
    		$this->widget_options,
    		array( 'number' => $number )
    	);

    	_register_widget_update_callback(
    		$this->id_base,
    		$this->_get_update_callback(),
    		$this->control_options,
    		array( 'number' => -1 )
    	);

    	_register_widget_form_callback(
    		$this->id,
    		$this->name,
    		$this->_get_form_callback(),
    		$this->control_options,
    		array( 'number' => $number )
    	);
    }
    ```

[View all references](https://developer.wordpress.org/reference/files/wp-includes/class-wp-widget.php/)
[View on Trac](https://core.trac.wordpress.org/browser/tags/6.9.4/src/wp-includes/class-wp-widget.php#L567)
[View on GitHub](https://github.com/WordPress/wordpress-develop/blob/6.9.4/src/wp-includes/class-wp-widget.php#L567-L590)

## 󠀁[Related](https://developer.wordpress.org/reference/classes/wp_widget/_register_one/?output_format=md#related)󠁿

| Uses | Description | 
| [WP_Widget::_get_display_callback()](https://developer.wordpress.org/reference/classes/wp_widget/_get_display_callback/)`wp-includes/class-wp-widget.php` |

Retrieves the widget display callback.

  | 
| [WP_Widget::_get_update_callback()](https://developer.wordpress.org/reference/classes/wp_widget/_get_update_callback/)`wp-includes/class-wp-widget.php` |

Retrieves the widget update callback.

  | 
| [WP_Widget::_get_form_callback()](https://developer.wordpress.org/reference/classes/wp_widget/_get_form_callback/)`wp-includes/class-wp-widget.php` |

Retrieves the form callback.

  | 
| [wp_register_sidebar_widget()](https://developer.wordpress.org/reference/functions/wp_register_sidebar_widget/)`wp-includes/widgets.php` |

Registers an instance of a widget.

  | 
| [_register_widget_update_callback()](https://developer.wordpress.org/reference/functions/_register_widget_update_callback/)`wp-includes/widgets.php` |

Registers the update callback for a widget.

  | 
| [_register_widget_form_callback()](https://developer.wordpress.org/reference/functions/_register_widget_form_callback/)`wp-includes/widgets.php` |

Registers the form callback for a widget.

  |

[Show 1 more](https://developer.wordpress.org/reference/classes/wp_widget/_register_one/?output_format=md#)
[Show less](https://developer.wordpress.org/reference/classes/wp_widget/_register_one/?output_format=md#)

| Used by | Description | 
| [WP_Widget_Text::_register_one()](https://developer.wordpress.org/reference/classes/wp_widget_text/_register_one/)`wp-includes/widgets/class-wp-widget-text.php` |

Adds hooks for enqueueing assets when registering all widget instances of this widget class.

  | 
| [WP_Widget_Custom_HTML::_register_one()](https://developer.wordpress.org/reference/classes/wp_widget_custom_html/_register_one/)`wp-includes/widgets/class-wp-widget-custom-html.php` |

Add hooks for enqueueing assets when registering all widget instances of this widget class.

  | 
| [WP_Widget_Media::_register_one()](https://developer.wordpress.org/reference/classes/wp_widget_media/_register_one/)`wp-includes/widgets/class-wp-widget-media.php` |

Add hooks while registering all widget instances of this widget class.

  | 
| [WP_Widget::_register()](https://developer.wordpress.org/reference/classes/wp_widget/_register/)`wp-includes/class-wp-widget.php` |

Register all widget instances of this widget class.

  |

## 󠀁[Changelog](https://developer.wordpress.org/reference/classes/wp_widget/_register_one/?output_format=md#changelog)󠁿

| Version | Description | 
| [2.8.0](https://developer.wordpress.org/reference/since/2.8.0/) | Introduced. |

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