generate_do_element_classes

hiya nice GP peeps 🙂

i’m trying to implement the generate_do_element_classes functionality in a theme i’m creating from scratch (as a self-taught tutorial), but i’m getting Undefined variable: classes error and a warning that join() has too few args (1).

the code does output part of the attribute in the target element but the string is empty, like this class=""

i really enjoy learning how GP code works and would greatly appreciate any guidance if you have a moment… no worries if not.

thank you <3!

my theme-functions.php:

function mysite_do_element_classes( $context, $class = '' ) {
	$after = apply_filters( 'mysite_after_element_class_attribute', '',
                                   $context );

	if ( $after ) {
		$after = ' ' . $after;
	}

 	echo 'class="' . join( ' ', mysite_get_element_classes( $context, $class ) ) . '"' . $after;
}

function mysite_get_element_classes( $context, $class = '' ) {
	$classes = array();

	if ( ! empty( $class ) ) {
		if ( ! is_array( $class ) ) {
			$class = preg_split( '#\s+#', $class );
		}

		$classes = array_merge( $classes, $class );
	}

	$classes = array_map( 'esc_attr', $classes );

	return apply_filters( "mysite_create_{$context}_class", $classes, $class );
}

my markup.php:

if ( ! function_exists( 'mysite_create_header_classes' ) ) {
  add_filter( 'mysite_create_header_class',   
    'mysite_create_header_classes' );

	function mysite_create_header_classes( $classes ) {

		$classes[] = 'site-header';
	}
	return $classes;
}