Multilple single-use widgets with the same output callback

Question

I have this scenario where I need to provide various single-use widgets.

They're all displayed the same way, so I don't feel the need for a different display functions for each widget. However, if I use the same callback on all wp_register_sidebar_widget instances, only the last one is active.

I'm forced to have multiple identical functions, differing only the name. How can I improve it?

add_action( 'widgets_init', 'register_single_use_widgets' );
function register_single_use_widgets() {

  $id = 'first';
  $name = 'First Widget';
  $widget_ops = array( 'description' => 'This is the first widget.' );
  wp_register_sidebar_widget( $id, $name, 'single_widget_display', $widget_ops );

  $id = 'second';
  $name = 'Second Widget';
  $widget_ops = array( 'description' => 'This is the second widget.' );
  wp_register_sidebar_widget( $id, $name, 'single_widget_display2', $widget_ops );

  $id = 'third';
  $name = 'Third Widget';
  $widget_ops = array( 'description' => 'This is the third widget.' );
  wp_register_sidebar_widget( $id, $name, 'single_widget_display3', $widget_ops );

}

function single_widget_display( $args ) {
  $name = $args['widget_name'];
  echo "<p> $name </p>";
}

function single_widget_display2( $args ) {
  $name = $args['widget_name'];
  echo "<p> $name </p>";
}

function single_widget_display3( $args ) {
  $name = $args['widget_name'];
  echo "<p> $name </p>";
}

Answer 1

It appears that wp_register_sidebar_widget is a very outdated function from early implementations of widgets. Apparently back then widgets could only be used once each and the output callback name seems to be what made a widget unique, despite the existence of an ID. The single-use nature of these widgets doesn't appear to be an intentional feature.

Given it's age I would suggest using the newer API, based on register_widget(). To register 3 widgets with the same output you would create a class for the widget, with some additionaland register 3 different instances of it.

function wpse_292985_widget_display( $args ) {
    echo '<p>' . $args['widget_name'] . '</p>';
}

class WPSE_292985_Widget extends WP_Widget {
    function __construct( $id, $name, $widget_ops ) {
        parent::__construct( $id, $name, $widget_ops );
    }

    function widget( $args, $instance ) {
        wpse_292985_widget_display( $args );
    }
}

function wpse_292985_register_widgets() {
    register_widget( new WPSE_292985_Widget( 
        'first', 
        'First Widget', 
        ['description' => 'This is the first widget.']
    ) );

    register_widget( new WPSE_292985_Widget( 
        'second', 
        'Second Widget', 
        ['description' => 'This is the second widget.']
    ) );

    register_widget( new WPSE_292985_Widget( 
        'third', 
        'Third Widget', 
        ['description' => 'This is the third widget.']
    ) );
}
add_action( 'widgets_init', 'wpse_292985_register_widgets' );

The first thing happening there is defining the function we want the widget to output. It accepts $args as an argument which we'll pass through in our widget class.

The next bit is the class for the Widget. This class is just a copy of the generic WordPress widget class, but we're setting the widget() method here to output our function.

Then we register 3 widgets by creating new instances of our widget class and passing them into register_widget().