- <?php wp_dropdown_categories( array( 'taxonomy' => $tax_name, 'hide_empty' => 0, 'name' => 'new' . $tax_name . '_parent', 'orderby' => 'name', 'hierarchical' => 1, 'show_option_none' => '— ' . $taxonomy->labels->parent_item . ' —' ) ); ?>
+ <?php
+ $parent_dropdown_args = array(
+ 'taxonomy' => $tax_name,
+ 'hide_empty' => 0,
+ 'name' => 'new' . $tax_name . '_parent',
+ 'orderby' => 'name',
+ 'hierarchical' => 1,
+ 'show_option_none' => '— ' . $taxonomy->labels->parent_item . ' —',
+ );
+
+ /**
+ * Filter the arguments for the taxonomy parent dropdown on the Post Edit page.
+ *
+ * @since 4.4.0
+ *
+ * @param array $parent_dropdown_args {
+ * Optional. Array of arguments to generate parent dropdown.
+ *
+ * @type string $taxonomy Name of the taxonomy to retrieve.
+ * @type bool $hide_if_empty True to skip generating markup if no
+ * categories are found. Default 0.
+ * @type string $name Value for the 'name' attribute
+ * of the select element.
+ * Default "new{$tax_name}_parent".
+ * @type string $orderby Which column to use for ordering
+ * terms. Default 'name'.
+ * @type bool|int $hierarchical Whether to traverse the taxonomy
+ * hierarchy. Default 1.
+ * @type string $show_option_none Text to display for the "none" option.
+ * Default "— {$parent} —",
+ * where `$parent` is 'parent_item'
+ * taxonomy label.
+ * }
+ */
+ $parent_dropdown_args = apply_filters( 'post_edit_category_parent_dropdown_args', $parent_dropdown_args );
+
+ wp_dropdown_categories( $parent_dropdown_args );
+ ?>