How to initialize $id from another function?

Question

I would like to use $id to echo the id entered in other functions. Here is an example function using id:

                function nl_register_ga_code() {
                    // Validation callback
                    register_setting( 'nl_theme_options', 'nl_theme_options', 'nl_validate_settings' );
                    // Add setting to section
                    add_settings_section( 'nl_footer_section', 'Footer', 'nl_display_footer_section', 'nl_theme_options.php' );
                    // Create textarea field
                    $field_args = array(
                        'type'      => 'textarea',
                        'id'        => 'nl_ga_code',
                        'name'      => 'nl_ga_code',
                        'desc'      => 'Paste Google Analytics code.',
                        'std'       => '',
                        'label_for' => 'nl_ga_code'
                    );
                    // Label
                    add_settings_field( 'label_ga_code', 'Google Analytics Code', 'nl_display_setting', 'nl_theme_options.php', 'nl_footer_section', $field_args );
                }
                // Registers the setting
                add_action( 'admin_init', 'nl_register_ga_code' );

The function I will be using the variable is this one:

        function nl_display_setting ( $args ) {
            extract( $args );
            $option_name = 'nl_theme_options';
            $options = get_option( $option_name );
            switch ( $type ) {  
                case 'text':
                        $options[$id] = stripslashes( $options[$id] );
                        $options[$id] = esc_attr( $options[$id] );
                    echo "<input class='regular-text$class' type='text' id='$id' name='" . $option_name . "[$id]' value='$options[$id]'>";
                    echo ( $desc != '' ) ? "<br><span class='description'>$desc</span>" : "";
                break;

I need to initialize $id but do not know how.

Answer 1

From this question and your prior question, it looks like you are passing $field_args from nl_register_ga_code() to nl_display_setting(), like this nl_display_setting($field_args). (If not, then you should be -- based on your comments, that's what you're trying to do.)

So, in nl_display_setting(), don't refer to $id, $type, or $desc; refer to $args['id'], $args['type'], and $args['desc'], respectively.

You cannot refer to an array key as though it were a standalone variable. So, if you have this:

$foo = array('bar' => 1234);

You can't use $bar to get 1234, but you can use $foo['bar'] to get it.