WP_Widget_Categories::widget( array $args, array $instance )

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$argsarray

Display arguments including 'before_title', 'after_title', 'before_widget', and 'after_widget'.

$instancearray

Settings for the current Categories widget instance.

Performance profile

How much work a call to WP_Widget_Categories::widget() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Heavy

Reaches the database via get_terms().

Scaling

Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions

71–110

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 163.

Plugin surface

4 hooks

Third-party callbacks on 'widget_title', 'widget_categories_dropdown_args', 'navigation_widgets_format' run inside this call, and their cost is not bounded by anything here.

Called by

0

Nothing in core calls this; the cost is only what you spend yourself.

What it touches

• hookthird-party callbacksapply_filters()called directly
• querycontent queryget_terms()one call below WP_Widget_Categories::widget()
• optionoption read or writeget_option()one call below WP_Widget_Categories::widget()

Further down the call graph this can also reach cache, serialize and transient. Those are the worst case, several calls deep and usually down an error path, not what a normal call pays.

What one call costs · 3 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost WP_Widget_Categories::widget() can have, taken from its control-flow graph on PHP 8.5.

Hooks and filters fired · 4

4 hooks fire while WP_Widget_Categories::widget() runs, in this order:

1. 1
   apply_filters( widget_title )filterline 52 (+7 into the body)

   Filters the widget title.

2. 2
   apply_filters( widget_categories_dropdown_args )filterline 91 (+46 into the body)

   Filters the arguments for the Categories widget drop-down.

3. 3
   apply_filters( navigation_widgets_format )filterline 116 (+71 into the body)

   Filters the HTML format of widgets with navigation links.

4. 4
   apply_filters( widget_categories_args )filterline 139 (+94 into the body)

   Filters the arguments for the Categories widget.

Uses · 11

• __()Retrieves the translation of $text.
• apply_filters()Calls the callback functions that have been added to a filter hook.
• esc_url()Checks and cleans a URL.
• home_url()Retrieves the URL for the current site where the front end is accessible.
• esc_attr()Escaping for HTML attributes.
• wp_dropdown_categories()Displays or retrieves the HTML dropdown list of categories.
• esc_js()Escapes single quotes, `"`, ``, `&`, and fixes line endings.
• wp_print_inline_script_tag()Prints an inline script tag.
• wp_remove_surrounding_empty_script_tags()Removes leading and trailing _empty_ script tags.
• current_theme_supports()Checks a theme's support for a given feature.
• wp_list_categories()Displays or retrieves the HTML list of categories.

Source code

View on Trac ↗View on GitHub ↗

45	public function widget( $args, $instance ) {46		static $first_dropdown = true;47 48		$default_title = __( 'Categories' );49		$title         = ! empty( $instance['title'] ) ? $instance['title'] : $default_title;50 51		/** This filter is documented in wp-includes/widgets/class-wp-widget-pages.php */52		$title = apply_filters( 'widget_title', $title, $instance, $this->id_base );53 54		$count        = ! empty( $instance['count'] ) ? '1' : '0';55		$hierarchical = ! empty( $instance['hierarchical'] ) ? '1' : '0';56		$dropdown     = ! empty( $instance['dropdown'] ) ? '1' : '0';57 58		echo $args['before_widget'];59 60		if ( $title ) {61			echo $args['before_title'] . $title . $args['after_title'];62		}63 64		$cat_args = array(65			'orderby'      => 'name',66			'show_count'   => $count,67			'hierarchical' => $hierarchical,68		);69 70		if ( $dropdown ) {71			printf( '<form action="%s" method="get">', esc_url( home_url() ) );72			$dropdown_id    = ( $first_dropdown ) ? 'cat' : "{$this->id_base}-dropdown-{$this->number}";73			$first_dropdown = false;74 75			echo '<label class="screen-reader-text" for="' . esc_attr( $dropdown_id ) . '">' . $title . '</label>';76 77			$cat_args['show_option_none'] = __( 'Select Category' );78			$cat_args['id']               = $dropdown_id;79 80			/**81			 * Filters the arguments for the Categories widget drop-down.82			 *83			 * @since 2.8.084			 * @since 4.9.0 Added the `$instance` parameter.85			 *86			 * @see wp_dropdown_categories()87			 *88			 * @param array $cat_args An array of Categories widget drop-down arguments.89			 * @param array $instance Array of settings for the current widget.90			 */91			wp_dropdown_categories( apply_filters( 'widget_categories_dropdown_args', $cat_args, $instance ) );92 93			echo '</form>';94 95			ob_start();96			?>97 98<script>99(function() {100	var dropdown = document.getElementById( "<?php echo esc_js( $dropdown_id ); ?>" );101	function onCatChange() {102		if ( dropdown.options[ dropdown.selectedIndex ].value > 0 ) {103			dropdown.parentNode.submit();104		}105	}106	dropdown.onchange = onCatChange;107})();108</script>109 110			<?php111			wp_print_inline_script_tag( wp_remove_surrounding_empty_script_tags( ob_get_clean() ) );112		} else {113			$format = current_theme_supports( 'html5', 'navigation-widgets' ) ? 'html5' : 'xhtml';114 115			/** This filter is documented in wp-includes/widgets/class-wp-nav-menu-widget.php */116			$format = apply_filters( 'navigation_widgets_format', $format );117 118			if ( 'html5' === $format ) {119				// The title may be filtered: Strip out HTML and make sure the aria-label is never empty.120				$title      = trim( strip_tags( $title ) );121				$aria_label = $title ? $title : $default_title;122				echo '<nav aria-label="' . esc_attr( $aria_label ) . '">';123			}124			?>

Changelog

Introduced in 2.8.0. Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data

Generated from the wordpress-develop 6.7.7 tag, from src/wp-includes/widgets/class-wp-widget-categories.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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