这是一段有详细注释的WordPress自定义小工具（Widget ）开发实例代码，可用于制作主题时集成自定义小工具，将代码添加到主题functions.php中，具体效果如图：

<?php/**  * Add function to widgets_init that'll load our widget.  * @since 0.1  */add_action( 'widgets_init', 'example_load_widgets' );/**  * Register our widget.  * 'Example_Widget' is the widget class used below.  *  * @since 0.1  */function example_load_widgets() {    register_widget( 'Example_Widget' );}/**  * Example Widget class.  * This class handles everything that needs to be handled with the widget:  * the settings, form, display, and update.  Nice!  *  * @since 0.1  */class Example_Widget extends WP_Widget {    /**      * Widget setup.      */    function Example_Widget() {        /* Widget settings. */        $widget_ops = array( 'classname' => 'example', 'description' => __('An example widget that displays a person's name and sex.', 'example') );        /* Widget control settings. */        $control_ops = array( 'width' => 300, 'height' => 350, 'id_base' => 'example-widget' );        /* Create the widget. */        $this->WP_Widget( 'example-widget', __('Example Widget', 'example'), $widget_ops, $control_ops );    }    /**      * How to display the widget on the screen.      */    function widget( $args, $instance ) {        extract( $args );        /* Our variables from the widget settings. */        $title = apply_filters('widget_title', $instance['title'] );        $name = $instance['name'];        $sex = $instance['sex'];        $show_sex = isset( $instance['show_sex'] ) ? $instance['show_sex'] : false;        /* Before widget (defined by themes). */        echo $before_widget;        /* Display the widget title if one was input (before and after defined by themes). */        if ( $title )            echo $before_title . $title . $after_title;        /* Display name from widget settings if one was input. */        if ( $name )            printf( '<p>' . __('Hello. My name is %1$s.', 'example') . '</p>', $name );        /* If show sex was selected, display the user's sex. */        if ( $show_sex )            printf( '<p>' . __('I am a %1$s.', 'example.') . '</p>', $sex );        /* After widget (defined by themes). */        echo $after_widget;    }    /**      * Update the widget settings.      */    function update( $new_instance, $old_instance ) {        $instance = $old_instance;        /* Strip tags for title and name to remove HTML (important for text inputs). */        $instance['title'] = strip_tags( $new_instance['title'] );        $instance['name'] = strip_tags( $new_instance['name'] );        /* No need to strip tags for sex and show_sex. */        $instance['sex'] = $new_instance['sex'];        $instance['show_sex'] = $new_instance['show_sex'];        return $instance;    }    /**      * Displays the widget settings controls on the widget panel.      * Make use of the get_field_id() and get_field_name() function      * when creating your form elements. This handles the confusing stuff.      */    function form( $instance ) {        /* Set up some default widget settings. */        $defaults = array( 'title' => __('Example', 'example'), 'name' => __('John Doe', 'example'), 'sex' => 'male', 'show_sex' => true );        $instance = wp_parse_args( (array) $instance, $defaults ); ?>        <!-- Widget Title: Text Input -->        <p>            <label for="<?php echo $this->get_field_id( 'title' ); ?>"><?php _e('Title:', 'hybrid'); ?></label>            <input id="<?php echo $this->get_field_id( 'title' ); ?>" name="<?php echo $this->get_field_name( 'title' ); ?>" value="<?php echo $instance['title']; ?>" style="width:100%;" />        </p>        <!-- Your Name: Text Input -->        <p>            <label for="<?php echo $this->get_field_id( 'name' ); ?>"><?php _e('Your Name:', 'example'); ?></label>            <input id="<?php echo $this->get_field_id( 'name' ); ?>" name="<?php echo $this->get_field_name( 'name' ); ?>" value="<?php echo $instance['name']; ?>" style="width:100%;" />        </p>        <!-- Sex: Select Box -->        <p>            <label for="<?php echo $this->get_field_id( 'sex' ); ?>"><?php _e('Sex:', 'example'); ?></label>            <select id="<?php echo $this->get_field_id( 'sex' ); ?>" name="<?php echo $this->get_field_name( 'sex' ); ?>" class="widefat" style="width:100%;">                <option <?php if ( 'male' == $instance['format'] ) echo 'selected="selected"'; ?>>male</option>                <option <?php if ( 'female' == $instance['format'] ) echo 'selected="selected"'; ?>>female</option>            </select>        </p>        <!-- Show Sex? Checkbox -->        <p>            <input class="checkbox" type="checkbox" <?php checked( $instance['show_sex'], true ); ?> id="<?php echo $this->get_field_id( 'show_sex' ); ?>" name="<?php echo $this->get_field_name( 'show_sex' ); ?>" />            <label for="<?php echo $this->get_field_id( 'show_sex' ); ?>"><?php _e('Display sex publicly?', 'example'); ?></label>        </p>    <?php    }}?>