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| Date | Sat, 10 May 2014 12:33:28 +1000 |
| Subject | Re: Values and objects |
| From | Chris Angelico <rosuav@gmail.com> |
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On Sat, May 10, 2014 at 12:19 PM, Rustom Mody <rustompmody@gmail.com> wrote: > For me, Marko's comment that variables in python are not first-class > whereas in C they are is for me the most important distinction Ive seen > (in a long time of seeing these discussions). > https://en.wikipedia.org/wiki/First-class_citizen For variables in C to be considered first-class, they must, by most definitions, be able to be passed around as parameters and return values. Some definitions also require that they be able to be constructed at run-time. How do C variables shape up? 1) Passing them as parameters. You can pass a pointer to a variable, which is effectively the same as passing a variable to a function. The callee can mutate your variable through the pointer. 2) Returning them. This is a lot more dodgy, owing to the dangling-pointer issue, but as long as you accept that the reference to a variable doesn't ensure its continued life, I suppose this might be acceptable. Maybe. But it's pushing it. 3) Constructing at run-time. Really REALLY pushing it. You can malloc and call that a "variable", but it's not a variable any more, it's just a patch of memory. In fact, all this proves is that variables represent patches of memory, and patches of memory are first-class. Not liking the results here. You might just as well define that all Python variables must be backed by a dictionary (it's just as true as "all C variables must be backed by memory") and then define the first-class-variable as a combination of a dict and a key. ChrisA
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Re: Pass variable by reference Ned Batchelder <ned@nedbatchelder.com> - 2014-05-06 16:31 -0400
Re: Pass variable by reference Mark H Harris <harrismh777@gmail.com> - 2014-05-06 16:00 -0500
Re: Pass variable by reference Ned Batchelder <ned@nedbatchelder.com> - 2014-05-06 17:27 -0400
Re: Pass variable by reference Chris Angelico <rosuav@gmail.com> - 2014-05-07 09:46 +1000
Re: Pass variable by reference Rustom Mody <rustompmody@gmail.com> - 2014-05-06 19:18 -0700
Re: Pass variable by reference Chris Angelico <rosuav@gmail.com> - 2014-05-07 12:39 +1000
Re: Pass variable by reference Rustom Mody <rustompmody@gmail.com> - 2014-05-06 19:54 -0700
Re: Pass variable by reference Steven D'Aprano <steve@pearwood.info> - 2014-05-07 04:59 +0000
Re: Pass variable by reference Mark H Harris <harrismh777@gmail.com> - 2014-05-07 13:11 -0500
Re: Pass variable by reference Marko Rauhamaa <marko@pacujo.net> - 2014-05-08 00:22 +0300
Values and objects [was Re: Pass variable by reference] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-08 01:08 +0000
Re: Values and objects [was Re: Pass variable by reference] Mark H Harris <harrismh777@gmail.com> - 2014-05-09 16:56 -0500
Re: Values and objects Marko Rauhamaa <marko@pacujo.net> - 2014-05-10 01:34 +0300
Re: Values and objects Ben Finney <ben@benfinney.id.au> - 2014-05-10 10:24 +1000
Re: Values and objects Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-10 01:01 +0000
Re: Values and objects Rustom Mody <rustompmody@gmail.com> - 2014-05-09 19:19 -0700
Re: Values and objects Chris Angelico <rosuav@gmail.com> - 2014-05-10 12:33 +1000
Re: Values and objects Rustom Mody <rustompmody@gmail.com> - 2014-05-09 20:05 -0700
Re: Values and objects Mark H Harris <harrismh777@gmail.com> - 2014-05-09 23:15 -0500
Re: Values and objects Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-10 06:15 +0000
Re: Values and objects Chris Angelico <rosuav@gmail.com> - 2014-05-10 17:21 +1000
Re: Values and objects Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-10 09:09 +0000
Re: Values and objects Chris Angelico <rosuav@gmail.com> - 2014-05-10 19:32 +1000
Re: Values and objects Ethan Furman <ethan@stoneleaf.us> - 2014-05-10 12:10 -0700
Re: Values and objects MRAB <python@mrabarnett.plus.com> - 2014-05-10 20:22 +0100
Re: Values and objects Ethan Furman <ethan@stoneleaf.us> - 2014-05-10 12:28 -0700
Re: Values and objects Terry Reedy <tjreedy@udel.edu> - 2014-05-10 16:16 -0400
Re: Values and objects Terry Reedy <tjreedy@udel.edu> - 2014-05-10 16:24 -0400
Re: Values and objects Devin Jeanpierre <jeanpierreda@gmail.com> - 2014-05-10 14:03 -0700
Re: Values and objects Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-11 03:17 +0000
Re: Values and objects Chris Angelico <rosuav@gmail.com> - 2014-05-11 13:30 +1000
Re: Values and objects Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-11 05:11 +0000
Re: Values and objects Chris Angelico <rosuav@gmail.com> - 2014-05-11 15:22 +1000
Re: Values and objects Rustom Mody <rustompmody@gmail.com> - 2014-05-10 22:31 -0700
Re: Values and objects Marko Rauhamaa <marko@pacujo.net> - 2014-05-11 09:21 +0300
Re: Values and objects Rustom Mody <rustompmody@gmail.com> - 2014-05-10 23:48 -0700
Re: Values and objects Marko Rauhamaa <marko@pacujo.net> - 2014-05-11 18:10 +0300
Re: Values and objects Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2014-05-11 11:26 +0300
Re: Values and objects Rustom Mody <rustompmody@gmail.com> - 2014-05-11 01:48 -0700
Re: Values and objects Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2014-05-11 15:22 +0300
Re: Values and objects Marko Rauhamaa <marko@pacujo.net> - 2014-05-11 18:46 +0300
Re: Values and objects Marko Rauhamaa <marko@pacujo.net> - 2014-05-11 22:56 +0300
Re: Values and objects Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-11 12:51 +0000
Re: Values and objects Rustom Mody <rustompmody@gmail.com> - 2014-05-11 07:12 -0700
Re: Values and objects Ethan Furman <ethan@stoneleaf.us> - 2014-05-10 22:42 -0700
Re: Values and objects Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-11 06:40 +0000
Re: Values and objects Chris Angelico <rosuav@gmail.com> - 2014-05-11 09:18 +1000
Re: Values and objects Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-11 03:11 +0000
Re: Values and objects Rotwang <sg552@hotmail.co.uk> - 2014-05-11 14:46 +0100
Re: Values and objects Ned Batchelder <ned@nedbatchelder.com> - 2014-05-11 14:40 -0400
Re: Values and objects Rotwang <sg552@hotmail.co.uk> - 2014-05-12 00:06 +0100
Re: Values and objects Ethan Furman <ethan@stoneleaf.us> - 2014-05-10 18:28 -0700
Re: Values and objects Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-11 07:24 +0000
Re: Values and objects Chris Angelico <rosuav@gmail.com> - 2014-05-11 11:59 +1000
Re: Values and objects Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-11 07:29 +0000
Re: Values and objects Ethan Furman <ethan@stoneleaf.us> - 2014-05-10 21:46 -0700
Re: [Python-Dev] Values and objects Chris Angelico <rosuav@gmail.com> - 2014-05-11 16:08 +1000
Re: Values and objects albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-05-17 14:26 +0000
Re: Values and objects Chris Angelico <rosuav@gmail.com> - 2014-05-10 11:58 +1000
Re: Values and objects Marko Rauhamaa <marko@pacujo.net> - 2014-05-10 10:57 +0300
Re: Values and objects Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2014-05-10 11:06 +0300
Re: Values and objects Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-05-10 12:07 -0400
Re: Pass variable by reference Chris Angelico <rosuav@gmail.com> - 2014-05-08 11:31 +1000
Re: Pass variable by reference Mark H Harris <harrismh777@gmail.com> - 2014-05-09 17:30 -0500
Abstractions [was Re: Pass variable by reference] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-10 00:58 +0000
Re: Abstractions [was Re: Pass variable by reference] Mark H Harris <harrismh777@gmail.com> - 2014-05-09 21:17 -0500
Re: Pass variable by reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-05-07 01:14 +0000
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