Raymond Hettinger added the comment: This from the help on dict.update():
| update(...) | D.update([E, ]**F) -> None. Update D from dict/iterable E and F. | If E present and has a .keys() method, does: for k in E: D[k] = E[k] | If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v | In either case, this is followed by: for k in F: D[k] = F[k] Likewise in the source for collections.abc.MutableMapping: def update(*args, **kwds): ''' D.update([E, ]**F) -> None. Update D from mapping/iterable E and F. If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In either case, this is followed by: for k, v in F.items(): D[k] = v ''' if not args: raise TypeError("descriptor 'update' of 'MutableMapping' object " "needs an argument") self, *args = args if len(args) > 1: raise TypeError('update expected at most 1 arguments, got %d' % len(args)) if args: other = args[0] if isinstance(other, Mapping): for key in other: self[key] = other[key] elif hasattr(other, "keys"): for key in other.keys(): self[key] = other[key] else: for key, value in other: self[key] = value for key, value in kwds.items(): self[key] = value ---------- nosy: +rhettinger _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue30322> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com