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| References | (12 earlier) <557182af$0$13014$c3e8da3$5496439d@news.astraweb.com> <33a2f501-5587-4fd9-91fa-7094d4f6c512@googlegroups.com> <mailman.207.1433541572.13271.python-list@python.org> <81cb1232-ecf8-4cf0-b29c-ecf2ca47ade0@googlegroups.com> <55727c1c$0$13000$c3e8da3$5496439d@news.astraweb.com> |
|---|---|
| Date | 2015-06-06 15:29 +1000 |
| Subject | Re: Can Python function return multiple data? |
| From | Chris Angelico <rosuav@gmail.com> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.211.1433568557.13271.python-list@python.org> (permalink) |
On Sat, Jun 6, 2015 at 2:50 PM, Steven D'Aprano <steve@pearwood.info> wrote:
> This does not happen:
>
> mylist = []
> mytuple = (None, 1, mylist)
> mylist.append(0)
> => raises an exception
>
> The *tuple* is immutable, not the list.
What you could have is a "FrozenList" (by analogy with frozenset),
something like this:
class FrozenList(tuple):
def __new__(*a, **kw):
self = tuple.__new__(*a, **kw)
hash(self) # If error, disallow construction
return self
That would raise the error at the moment of mytuple's creation, not at
mylist's mutation, but that's about as close as I can think of to a
"this truly must be immutable" object in Python. And of course, any
object can lie (or be mistaken) about its hashability and mutability:
>>> def adder(x, inc=1): return x+inc
...
>>> hash(adder)
-9223363254790714706
>>> FrozenList((adder,))
(<function adder at 0x7fcbbcf0aae8>,)
>>> descr = {adder: "Add 1 to a number"}
Looks immutable to me.
>>> adder.__defaults__=2,
>>> next(iter(descr))(6)
8
Oops.
ChrisA
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Can Python function return multiple data? fl <rxjwg98@gmail.com> - 2015-06-02 14:27 -0700
Re: Can Python function return multiple data? Joel Goldstick <joel.goldstick@gmail.com> - 2015-06-02 17:35 -0400
Re: Can Python function return multiple data? sohcahtoa82@gmail.com - 2015-06-02 14:40 -0700
Re: Can Python function return multiple data? John Gordon <gordon@panix.com> - 2015-06-02 21:40 +0000
Re: Can Python function return multiple data? Chris Angelico <rosuav@gmail.com> - 2015-06-03 09:56 +1000
Re: Can Python function return multiple data? Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2015-06-03 15:56 +0200
Re: Can Python function return multiple data? Chris Angelico <rosuav@gmail.com> - 2015-06-04 07:35 +1000
Re: Can Python function return multiple data? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-03 22:56 +0100
Re: Can Python function return multiple data? sohcahtoa82@gmail.com - 2015-06-03 15:28 -0700
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Re: Can Python function return multiple data? Chris Angelico <rosuav@gmail.com> - 2015-06-04 11:52 +1000
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-04 23:47 +1000
Re: Can Python function return multiple data? Marko Rauhamaa <marko@pacujo.net> - 2015-06-04 17:25 +0300
Re: Can Python function return multiple data? Grant Edwards <invalid@invalid.invalid> - 2015-06-04 14:37 +0000
Re: Can Python function return multiple data? Marko Rauhamaa <marko@pacujo.net> - 2015-06-04 18:04 +0300
Re: Can Python function return multiple data? Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-06-04 19:51 -0400
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-05 03:11 +1000
Re: Can Python function return multiple data? Marko Rauhamaa <marko@pacujo.net> - 2015-06-04 20:30 +0300
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Re: Can Python function return multiple data? random832@fastmail.us - 2015-06-04 13:30 -0400
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-05 08:31 +1000
Re: Can Python function return multiple data? Grant Edwards <invalid@invalid.invalid> - 2015-06-04 18:38 +0000
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-05 08:52 +1000
Re: Can Python function return multiple data? Chris Angelico <rosuav@gmail.com> - 2015-06-05 09:04 +1000
Re: Can Python function return multiple data? Grant Edwards <invalid@invalid.invalid> - 2015-06-05 02:02 +0000
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Re: Can Python function return multiple data? BartC <bc@freeuk.com> - 2015-06-04 21:52 +0100
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Re: Can Python function return multiple data? BartC <bc@freeuk.com> - 2015-06-05 01:16 +0100
Re: Can Python function return multiple data? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-05 02:40 +0100
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-05 11:48 +1000
Re: Can Python function return multiple data? BartC <bc@freeuk.com> - 2015-06-05 11:06 +0100
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Re: Can Python function return multiple data? BartC <bc@freeuk.com> - 2015-06-05 10:51 +0100
Re: Can Python function return multiple data? ElChino <elchino@cnn.cn> - 2015-06-04 17:37 +0200
Re: Can Python function return multiple data? Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-06-04 19:57 -0400
Re: Can Python function return multiple data? random832@fastmail.us - 2015-06-04 13:26 -0400
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-05 08:16 +1000
Re: Can Python function return multiple data? random832@fastmail.us - 2015-06-04 18:59 -0400
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-05 12:37 +1000
Re: Can Python function return multiple data? Rustom Mody <rustompmody@gmail.com> - 2015-06-04 20:16 -0700
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-05 21:06 +1000
Re: Can Python function return multiple data? Rustom Mody <rustompmody@gmail.com> - 2015-06-05 06:29 -0700
Re: Can Python function return multiple data? Chris Angelico <rosuav@gmail.com> - 2015-06-06 07:59 +1000
Re: Can Python function return multiple data? Rustom Mody <rustompmody@gmail.com> - 2015-06-05 20:20 -0700
Re: Can Python function return multiple data? random832@fastmail.us - 2015-06-05 23:28 -0400
Re: Can Python function return multiple data? Rustom Mody <rustompmody@gmail.com> - 2015-06-05 22:28 -0700
Re: Can Python function return multiple data? Chris Angelico <rosuav@gmail.com> - 2015-06-06 15:43 +1000
Lawful != Mutable (was Can Python function return multiple data?) Rustom Mody <rustompmody@gmail.com> - 2015-06-07 08:49 -0700
Re: Lawful != Mutable (was Can Python function return multiple data?) Chris Angelico <rosuav@gmail.com> - 2015-06-08 02:07 +1000
Re: Lawful != Mutable (was Can Python function return multiple data?) Rustom Mody <rustompmody@gmail.com> - 2015-06-07 09:20 -0700
Re: Lawful != Mutable (was Can Python function return multiple data?) Chris Angelico <rosuav@gmail.com> - 2015-06-08 02:34 +1000
Re: Lawful != Mutable (was Can Python function return multiple data?) Rustom Mody <rustompmody@gmail.com> - 2015-06-20 18:59 -0700
Re: Lawful != Mutable (was Can Python function return multiple data?) Chris Angelico <rosuav@gmail.com> - 2015-06-21 12:32 +1000
Re: Lawful != Mutable (was Can Python function return multiple data?) Rustom Mody <rustompmody@gmail.com> - 2015-06-20 19:50 -0700
Re: Lawful != Mutable (was Can Python function return multiple data?) Laura Creighton <lac@openend.se> - 2015-06-21 11:14 +0200
Re: Lawful != Mutable (was Can Python function return multiple data?) Ron Adam <ron3200@gmail.com> - 2015-06-21 08:55 -0400
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-07 15:51 +1000
Re: Can Python function return multiple data? Chris Angelico <rosuav@gmail.com> - 2015-06-06 13:49 +1000
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-06 14:50 +1000
Re: Can Python function return multiple data? Chris Angelico <rosuav@gmail.com> - 2015-06-06 15:29 +1000
Re: Can Python function return multiple data? Rustom Mody <rustompmody@gmail.com> - 2015-06-05 22:32 -0700
Re: Can Python function return multiple data? Dave Farrance <df@see.replyto.invalid> - 2015-06-06 07:52 +0100
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-07 15:53 +1000
Re: Can Python function return multiple data? random832@fastmail.us - 2015-06-05 08:21 -0400
Re: Can Python function return multiple data? Marko Rauhamaa <marko@pacujo.net> - 2015-06-05 16:37 +0300
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Re: Can Python function return multiple data? Michael Torrie <torriem@gmail.com> - 2015-06-04 11:36 -0600
Re: Can Python function return multiple data? random832@fastmail.us - 2015-06-04 13:51 -0400
Re: Can Python function return multiple data? Alain Ketterlin <alain@universite-de-strasbourg.fr.invalid> - 2015-06-04 20:17 +0200
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-05 08:45 +1000
Re: Can Python function return multiple data? Alain Ketterlin <alain@universite-de-strasbourg.fr.invalid> - 2015-06-05 08:59 +0200
Re: Can Python function return multiple data? Michael Torrie <torriem@gmail.com> - 2015-06-04 08:16 -0600
Re: Can Python function return multiple data? sohcahtoa82@gmail.com - 2015-06-05 11:55 -0700
Re: Can Python function return multiple data? random832@fastmail.us - 2015-06-04 01:01 -0400
Re: Can Python function return multiple data? Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-04 12:34 -0600
Re: Can Python function return multiple data? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-04 20:16 +0100
Re: Can Python function return multiple data? Serhiy Storchaka <storchaka@gmail.com> - 2015-06-04 09:56 +0300
Re: Can Python function return multiple data? fl <rxjwg98@gmail.com> - 2015-06-06 10:57 -0700
Re: Can Python function return multiple data? Rustom Mody <rustompmody@gmail.com> - 2015-06-06 21:35 -0700
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-07 15:47 +1000
Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-07 15:33 +1000
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