    # File lib/sqlite3/driver/dl/driver.rb, line 280
          def commit_hook( db, data=nil, &block )
            @commit_hook_handler = block

            unless @commit_hook_handler_callback
              @commit_hook_handler_callback = ::DL.callback( "IP" ) do |cookie|
                @commit_hook_handler.call( cookie )
              end
            end

            API.sqlite3_commit_hook( db, block&&@commit_hook_handler_callback,
              data )
          end