I can see this being useful if I have a Django Rest Framework validate method (http://www.django-rest-framework.org/api-guide/serializers/#object-level-val...) which takes a dictionary argument. def validate(self, data): {'name': name, 'address': address} = data Currently, this would look like: def validate(self, data): name, address = data['name'], data['address'] It does get more useful with the extension: def validate(self, data): {'name': name, 'address': address, **rest} = data instead of: def validate(self, data): rest = data.copy() name = rest.pop('name') address = rest.pop('address') In the rest framework case, mutating data directly might not be a problem, but this does feel like a nice syntax when avoiding mutation is required. Regards, Ian On 25/05/16 14:11, Michael Selik wrote:
Python's iterable unpacking is what Lispers might call a destructuring bind.
py> iterable = 1, 2, 3, 4, 5 py> a, b, *rest = iterable py> a, b, rest (1, 2, (3, 4, 5))
Clojure also supports mapping destructuring. Let's add that to Python!
py> mapping = {"a": 1, "b": 2, "c": 3} py> {"a": x, "b": y, "c": z} = mapping py> x, y, z (1, 2, 3) py> {"a": x, "b": y} = mapping Traceback: ValueError: too many keys to unpack
This will be approximately as helpful as iterable unpacking was before PEP 3132 (https://www.python.org/dev/peps/pep-3132/).
I hope to keep discussion in this thread focused on the most basic form of dict unpacking, but we could extended mapping unpacking similarly to how PEP 3132 extended iterable unpacking. Just brainstorming...
py> mapping = {"a": 1, "b": 2, "c": 3} py> {"a": x, **rest} = mapping py> x, rest (1, {"b": 2, "c": 3})
_______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/