Source

File: wp-admin/includes/class-wp-list-table-compat.php

class _WP_List_Table_Compat extends WP_List_Table {
	public $_screen;
	public $_columns;

	public function __construct( $screen, $columns = array() ) {
		if ( is_string( $screen ) ) {
			$screen = convert_to_screen( $screen );
		}

		$this->_screen = $screen;

		if ( ! empty( $columns ) ) {
			$this->_columns = $columns;
			add_filter( 'manage_' . $screen->id . '_columns', array( $this, 'get_columns' ), 0 );
		}
	}

	/**
	 * @return array
	 */
	protected function get_column_info() {
		$columns  = get_column_headers( $this->_screen );
		$hidden   = get_hidden_columns( $this->_screen );
		$sortable = array();
		$primary  = $this->get_default_primary_column_name();

		return array( $columns, $hidden, $sortable, $primary );
	}

	/**
	 * @return array
	 */
	public function get_columns() {
		return $this->_columns;
	}
}