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[Python-ideas] Delayed Execution via Keyword
Abe Dillonabedillon at gmail.com
Fri Feb 17 12:12:08 EST 2017
Actually, following from the idea that packing and unpacking variablesshould be delayed by default, it might make sense to use syntax like:>>> a = *(2+2)>>> b = a + 1Instead of>>> a = lazy 2+2 # or whatever you want the keyword to be>>> b = a + 1That syntax sort-of resembles generator expressions, however; I usuallylike how python favors actual words over obscure symbol combinations forreadability's sake.On Fri, Feb 17, 2017 at 10:57 AM, Abe Dillon <abedillon at gmail.com> wrote:> I'd like to suggest a shorter keyword: `lazy`>> This isn't an endorsement. I haven't had time to digest how big this> change would be.>> If this is implemented, I'd also like to suggest that perhaps packing and> unpacking should be delayed by default and not evaluated until the contents> are used. It might save on many pesky edge cases that would evaluate your> expression unnecessarily.>> On Fri, Feb 17, 2017 at 10:43 AM, Joseph Hackman <josephhackman at gmail.com>> wrote:>>> Agreed. I think this may require some TLC to get right, but posting here>> for feedback on the idea overall seemed like a good start. As far as I>> know, the basic list and dict do not inspect what they contain. I.e.>>>> d = {}>> d['a']= delayed: stuff()>> b=d['a']>>>> b would end up as still the thunk, and stuff wouldn't be executed until>> either d['a'] or b actually is read from.>>>> -Joseph>>>> > On Feb 17, 2017, at 11:34 AM, Chris Angelico <rosuav at gmail.com> wrote:>> >>> >> On Sat, Feb 18, 2017 at 3:29 AM, Joseph Hackman <>>josephhackman at gmail.com> wrote:>> >> ChrisA: I am not sure about collections. I think it may be fine to not>> special case it: if the act of putting it in the collection reads anything,>> then it is evaluated, and if it doesn't it isn't. The ideal design goal for>> this would be that all existing code continues to function as if the change>> wasn't made at all, except that the value is evaluated at a different time.>> >>>> >>> > Yeah, I'm just worried that it'll become useless without that. For>> > instance, passing arguments to a function that uses *a,**kw is going>> > to package your thunk into a collection, and that's how (eg) the>> > logging module will process it.>> >>> > It's not going to be easy to have a simple AND useful definition of>> > "this collapses the waveform, that keeps it in a quantum state", but>> > sorting that out is fairly key to the proposal.>> >>> > ChrisA>> > _______________________________________________>> > Python-ideas mailing list>> >Python-ideas at python.org>> >https://mail.python.org/mailman/listinfo/python-ideas>> > Code of Conduct:http://python.org/psf/codeofconduct/>> _______________________________________________>> Python-ideas mailing list>>Python-ideas at python.org>>https://mail.python.org/mailman/listinfo/python-ideas>> Code of Conduct:http://python.org/psf/codeofconduct/>>>>-------------- next part --------------An HTML attachment was scrubbed...URL: <http://mail.python.org/pipermail/python-ideas/attachments/20170217/1df8e304/attachment.html>
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