I'm currently working on a data export softare using 1000th of OrderedDicts. Sometime I iterate, and sometime I get part of it. Currently I have a wrapper doing: x, y , z = d(data).unpack('x', 'y', 'z', default=None) So I can see a use for it. And it's not the first time I wish I could do this. Although I think for a shortcut to lookup automatically the vars with the same name as the dict keys by default would be nice: {x, y, z} = data Le 25/05/2016 17:18, Paul Moore a écrit :
On 25 May 2016 at 14:11, Michael Selik <michael.selik@gmail.com> wrote:
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/).
Neither this, nor the **rest extension you proposed, does what I think would be the most common requirement - get a set of elements and *ignore* the rest:
mapping = {"a": 1, "b": 2, "c": 3} {"a": x, "b": y} = mapping # Note no error! x, y, z (1, 2)
I'd still like to see some real-world use cases though - there are lots of options as the above example demonstrates, and nothing to guide us in deciding which would be the most useful one to choose.
Paul _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/