Re: Can Python function return multiple data?

From	Grant Edwards <invalid@invalid.invalid>
Newsgroups	comp.lang.python
Subject	Re: Can Python function return multiple data?
Date	2015-06-05 02:02 +0000
Organization	PANIX Public Access Internet and UNIX, NYC
Message-ID	<mkqvv1$779$1@reader1.panix.com> (permalink)
References	(7 earlier) <87a8wf5z4l.fsf@elektro.pacujo.net> <mkpnqm$gfn$1@reader1.panix.com> <557086d6$0$13011$c3e8da3$5496439d@news.astraweb.com> <mkq5ur$cj6$1@reader1.panix.com> <5570d6b3$0$12993$c3e8da3$5496439d@news.astraweb.com>

Show all headers | View raw

On 2015-06-04, Steven D'Aprano <steve@pearwood.info> wrote:
> On Fri, 5 Jun 2015 04:38 am, Grant Edwards wrote:
>
>>>> But, discussing pass-by-this vs. pass-by-that without also discussing
>>>> the semantics of the assignment operator is rather pointless.
>>>
>>> No, that's a red-herring.
>> 
>> I don't think so. ??The reason that many people seem to confused
>> about Python's argument passing is that they don't understand what
>> assignment does.
>
> I don't see the connection, but do explain, I'm interested.

To many people the difference between pass-by-value and
pass-by-reference is what the effects are of assigning to the formal
parameter from within the function.  Using the model of "assignment"
they're used to using from FORTAN/C/C++ Python appears to behave
weirdly and inconsistently.

But, it's not really because the parameter passing mechnism is
something novel (it's not). It's because of what assignment does.
Python's parameter passing is quite simple: it's exactly the same as
an assignment: it binds a name within the funciton's namespacepace to
an object.  If you don't first understand that's what an assignment
does, then trying to explain the parameter passing using phrases
spelled 'pass-by-<whatever>' isn't going to help.

At least that's how it works in my head.  First, you have to
understand assignment.  Then you can understand what Python parameter
passing does.

Or to be a bit obtuse: Python parameters are passed by value, but all
values are references.

[I once had a CS prof who didn't know there was anything other than
pass-by-reference, but that's another story.]

--
Grant

Thread

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
          Re: Can Python function return multiple data? Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-06-03 21:30 -0400
          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
                Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-05 08:37 +1000
                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
                Re: Can Python function return multiple data? Alain Ketterlin <alain@universite-de-strasbourg.fr.invalid> - 2015-06-05 09:11 +0200
                Re: Can Python function return multiple data? Marko Rauhamaa <marko@pacujo.net> - 2015-06-05 12:27 +0300
                Re: Can Python function return multiple data? Alain Ketterlin <alain@universite-de-strasbourg.fr.invalid> - 2015-06-05 14:04 +0200
                Re: Can Python function return multiple data? BartC <bc@freeuk.com> - 2015-06-04 21:52 +0100
                Re: Can Python function return multiple data? Steven D'Aprano <steve@pearwood.info> - 2015-06-05 09:13 +1000
                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
                Re: Can Python function return multiple data? Chris Angelico <rosuav@gmail.com> - 2015-06-05 07:44 +1000
                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
                Re: Can Python function return multiple data? Rustom Mody <rustompmody@gmail.com> - 2015-06-04 19:07 -0700
            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

csiph-web