On Apr 11, 5:41 pm, MRAB <pyt... at mrabarnett.plus.com> wrote: > A new method like "updatedefault" may be better, IMHO. It would act > like "update" except that it wouldn't overwrite existing values. That's sounds good MRAB! After you mentioned this i had an epiphany... why not just add an extra argument to dict.update? >>> dict.update(D, clobberexistingkeys=False)