Re: [Python-ideas] Dictionary destructing and unpacking.

By the way, this is already in the CPython source code if I remember from when I worked on 448. The code for dict unpacking is merely blocked. I like this syntax from a purity standpoint, but I don't think I would use it that much. On Thursday, June 8, 2017 at 3:18:21 PM UTC-4, Nick Badger

Re: [Python-ideas] Dictionary destructing and unpacking.

a few notes: >From the OP: It would be cool to have a syntax that would unpack the dictionary to > values based on the names of the variables. Something perhaps like: > > a, b, c = **mydict > > which would assign the values of the keys 'a', 'b', 'c' to the variables. > a number of alternatives

Re: [Python-ideas] Dictionary destructing and unpacking.

I ha d not read all the e-mails in the thread - but just to announce to people eager for a similar feature - I have a package on pypi that enables one to do: In [74]: with extradict.MapGetter({'a': 1}) as d: ...: from d import a ...: In [75]: a Out[75]: 1 (just pip install extradict )

Re: [Python-ideas] Dictionary destructing and unpacking.

While I don't like that syntax, we do know that sets are unhashable, so we can be certain that that would be a TypeError if it was meant to construct a set containing a set. (ie. {{foo}} will always result in a TypeError in python). On Thu, Jun 8, 2017 at 1:40 PM Chris Angelico

Re: [Python-ideas] Dictionary destructing and unpacking.

On Fri, Jun 9, 2017 at 6:02 AM, MRAB wrote: > It could also be used on the RHS to pack: > a = 1 b = 2 c = 3 d = 4 foo = {{a, b, c, d}} The trouble with that is that it's syntactically identical to creating a set containing a set containing

Re: [Python-ideas] Dictionary destructing and unpacking.

On 2017-06-08 20:16, Nick Badger wrote: Well, it's not deliberately not destructive, but I'd be more in favor of dict unpacking-assignment if it were spelled more like this: >>> foo = {'a': 1, 'b': 2, 'c': 3, 'd': 4} >>> {'a': bar, 'b': baz, **rest} = foo >>> bar 1 >>>

Re: [Python-ideas] Dictionary destructing and unpacking.

Well, it's not deliberately not destructive, but I'd be more in favor of dict unpacking-assignment if it were spelled more like this: >>> foo = {'a': 1, 'b': 2, 'c': 3, 'd': 4} >>> {'a': bar, 'b': baz, **rest} = foo >>> bar 1 >>> baz 2 >>> rest {'c': 3, 'd': 4}

Re: [Python-ideas] Dictionary destructing and unpacking.

On 8 June 2017 at 17:49, Paul Moore wrote: > On 8 June 2017 at 08:15, Stephen J. Turnbull > wrote: >> If you like this feature, and wish it were in Python, I genuinely wish >> you good luck getting it in. My point is just that in

Re: [Python-ideas] Dictionary destructing and unpacking.

On Jun 8, 2017 1:35 AM, "Greg Ewing" wrote: C Anthony Risinger wrote: > Incredibly useful and intuitive, and for me again, way more generally > applicable than iterable unpacking. Maps are ubiquitous. > Maps with a known, fixed set of keys are relatively uncommon

Re: [Python-ideas] Dictionary destructing and unpacking.

Lucas Wiman writes: > > Maps with a known, fixed set of keys are relatively uncommon > > in Python, though. > > This is false in interacting with HTTP services, where frequently you're > working with deserialized JSON dictionaries you expect to be in a precise > format (and fail if not).

Re: [Python-ideas] Dictionary destructing and unpacking.

Hi Lucas, I would consider converting the dict into a namedtuple then. Essentially the namedtuple acts as a specification for expected fielsds: abc = namedtuple("ABC", "a b c") d = {"a":1, "b": 2, "c":3} # presumably you got this from reading some JSON abc(**d) # returns: ABC(a=1, b=2, c=3)

Re: [Python-ideas] Dictionary destructing and unpacking.

> > Maps with a known, fixed set of keys are relatively uncommon > in Python, though. This is false in interacting with HTTP services, where frequently you're working with deserialized JSON dictionaries you expect to be in a precise format (and fail if not). On Wed, Jun 7, 2017 at 11:32 PM,

Re: [Python-ideas] Dictionary destructing and unpacking.

C Anthony Risinger wrote: Incredibly useful and intuitive, and for me again, way more generally applicable than iterable unpacking. Maps are ubiquitous. Maps with a known, fixed set of keys are relatively uncommon in Python, though. Such an object is more likely to be an object with named

Re: [Python-ideas] Dictionary destructing and unpacking.

One existing way to do this: a, b, c = (mydict[k] for k in ('a', 'b', 'c')) -- Greg ___ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/

Re: [Python-ideas] Dictionary destructing and unpacking.

> In python 3.6+ this is better since the dictionary is insertion-ordered, but is still not really what one would probably want. Be careful: ordered dict is an implementation detail. You must use explicitly collections.OrderedDict() to avoid bad surprises. In CPython 3.7, dict might change

Re: [Python-ideas] Dictionary destructing and unpacking.

Thank you! This overview really helps! On Thu, Jun 08, 2017 at 11:18:06AM +1000, Steven D'Aprano wrote: > On Wed, Jun 07, 2017 at 06:14:08PM +, Nick Humrich wrote: > > > It would be cool to have a syntax that would unpack the dictionary to > > values based on the names

Re: [Python-ideas] Dictionary destructing and unpacking.

On Wed, Jun 07, 2017 at 06:14:08PM +, Nick Humrich wrote: > It would be cool to have a syntax that would unpack the dictionary to > values based on the names of the variables. Something perhaps like: > > a, b, c = **mydict This was discussed (briefly, to very little interest) in March/April

Re: [Python-ideas] Dictionary destructing and unpacking.

On Jun 7, 2017 5:54 PM, "Erik" wrote: On 07/06/17 23:42, C Anthony Risinger wrote: > Neither of these are really comparable to destructuring. > No, but they are comparable to the OP's suggested new built-in method (without requiring each mapping type - not just dicts

Re: [Python-ideas] Dictionary destructing and unpacking.

On Jun 7, 2017 5:42 PM, "C Anthony Risinger" wrote: On Jun 7, 2017 5:15 PM, "Matt Gilson" wrote: On Wed, Jun 7, 2017 at 3:11 PM, Erik wrote: > On 07/06/17 19:14, Nick Humrich wrote: > >> a, b, c = mydict.unpack('a',

Re: [Python-ideas] Dictionary destructing and unpacking.

On 07/06/17 23:42, C Anthony Risinger wrote: Neither of these are really comparable to destructuring. No, but they are comparable to the OP's suggested new built-in method (without requiring each mapping type - not just dicts - to implement it). That was what _I_ was responding to. E.

Re: [Python-ideas] Dictionary destructing and unpacking.

On Wed, Jun 7, 2017 at 3:11 PM, Erik wrote: > On 07/06/17 19:14, Nick Humrich wrote: > >> a, b, c = mydict.unpack('a', 'b', 'c') >> > > def retrieve(mapping, *keys): >return (mapping[key] for key in keys) > > > Or even: from operator import itemgetter retrieve =

Re: [Python-ideas] Dictionary destructing and unpacking.

On 07/06/17 19:14, Nick Humrich wrote: a, b, c = mydict.unpack('a', 'b', 'c') def retrieve(mapping, *keys): return (mapping[key] for key in keys) $ python3 Python 3.5.2 (default, Nov 17 2016, 17:05:23) [GCC 5.4.0 20160609] on linux Type "help", "copyright", "credits" or "license" for