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WordPress

Walker_PageDropdown::start_el( string $output, WP_Post $data_object, int $depth = 0, array $args = array(), int $current_object_id = 0 )

Since
2.1.0, 5.9.0
Source
wp-includes/class-walker-page-dropdown.php:62
Starts the element output.

Compatibility

WordPress
since 5.9.0
PHP
7.4–8.6-dev
  • 6.7.7
  • 6.8.8
  • 6.9.7
  • 7.0.4
  • 7.1.0

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

Parameters

$outputstring
Used to append additional content. Passed by reference.
$data_objectWP_Post
Page data object.
$depthintoptional
Depth of page in reference to parent pages.
Used for padding. Default 0.Default: 0
$argsarrayoptional
Uses 'selected' argument for selected page to set selected HTML attribute for option element. Uses 'value_field' argument to fill "value" attribute.
See wp_dropdown_pages(). Default empty array.Default: array()
$current_object_idintoptional
ID of the current page. Default 0.Default: 0

Performance profile

How much work a call to Walker_PageDropdown::start_el() 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
Trivial

Touches nothing outside its own arguments.

Scaling
Constant

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

Instructions
50–63

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 63.

Plugin surface
1 hook

Third-party callbacks on 'list_pages' 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

Further down the call graph this can also reach option, cache, serialize, query 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 · 2 distinct outcomes

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

WhenInstructionsCalls it makes
$title !== ""50–54str_repeat(), esc_attr(), apply_filters(), esc_html()
$title === ""59–63str_repeat(), esc_attr(), __(), sprintf(), apply_filters(), esc_html()

Across PHP versions

Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 63 instructions, 50–63 executed per call, 4 branches. The work does not change between versions.

An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.

Hooks and filters fired · 1

One hook fires while Walker_PageDropdown::start_el() runs, in this order:

  1. apply_filters( list_pages )filterline 92 (+30 into the body)

    Filters the page title when creating an HTML drop-down list of pages.

Uses · 4

  • esc_attr()Escaping for HTML attributes.
  • __()Retrieves the translation of $text.
  • apply_filters()Calls the callback functions that have been added to a filter hook.
  • esc_html()Escaping for HTML blocks.

Source code

View on Trac View on GitHub 

	public function start_el( &$output, $data_object, $depth = 0, $args = array(), $current_object_id = 0 ) {		// Restores the more descriptive, specific name for use within this method.		$page = $data_object; 		$pad = str_repeat( '&nbsp;', $depth * 3 ); 		if ( ! isset( $args['value_field'] ) || ! isset( $page->{$args['value_field']} ) ) {			$args['value_field'] = 'ID';		} 		$output .= "\t<option class=\"level-$depth\" value=\"" . esc_attr( $page->{$args['value_field']} ) . '"';		if ( $page->ID === (int) $args['selected'] ) {			$output .= ' selected="selected"';		}		$output .= '>'; 		$title = $page->post_title;		if ( '' === $title ) {			/* translators: %d: ID of a post. */			$title = sprintf( __( '#%d (no title)' ), $page->ID );		} 		/**		 * Filters the page title when creating an HTML drop-down list of pages.		 *		 * @since 3.1.0		 *		 * @param string  $title Page title.		 * @param WP_Post $page  Page data object.		 */		$title = apply_filters( 'list_pages', $title, $page ); 		$output .= $pad . esc_html( $title );		$output .= "</option>\n";	}

Changelog

Introduced in 2.1.0. 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.

5.9.0
Renamed $page to $data_object and $id to $current_object_id to match parent class for PHP 8 named parameter support.from the docblock
2.1.0
Introduced.from the docblock

About this page

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Generated from the wordpress-develop 7.0.4 tag, from src/wp-includes/class-walker-page-dropdown.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
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