Re: generator/coroutine terminology

From	Mark Lawrence <breamoreboy@yahoo.co.uk>
Subject	Re: generator/coroutine terminology
Date	2015-03-14 16:56 +0000
References	(10 earlier) <5503cf5f$0$12985$c3e8da3$5496439d@news.astraweb.com> <fa979c28-760a-4f50-8d74-862a70b03cfb@googlegroups.com> <83d579c1-ab61-4a3d-a834-e65d28eace8a@googlegroups.com> <mailman.359.1426349684.21433.python-list@python.org> <976313df-00f6-4845-a774-e5902b0fb2ce@googlegroups.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.361.1426352231.21433.python-list@python.org> (permalink)

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On 14/03/2015 16:33, Rustom Mody wrote:
> On Saturday, March 14, 2015 at 9:45:10 PM UTC+5:30, Chris Angelico wrote:
>> On Sun, Mar 15, 2015 at 2:59 AM, Rustom Mody wrote:
>>> Causing all sorts of unnecessary confusions:
>>> An int-function returns int and a char*-functions returns char*.
>>> Does a void-function return void??
>>> No a void function doesn't return anything!
>>> Ah So a void function does a longjmp?
>>>
>>> All of which is to say that in retrospect we need (at least in imperative programming) procedures and functions.
>>>
>>> Best if the language supports them
>>
>> Python has a broad concept of "functions/methods that return something
>> interesting" and "functions/methods that always return None". (The
>> distinction often corresponds to non-mutator and mutator methods, but
>> that's just convention.)
>
> With due respect Chris, you are confused:
>
> Sure any effective *pythonista* (who writes useful python) will have this concept.
>
> Python (as against pythonistas) has no such concept¹ as "function that ALWAYS
> returns None"
>
> Consider this foo
>
>>>> def foo(x):
> ...  if x>0: return x-1
> ...
>>>> foo(3)
> 2
>>>> foo(-1)
>>>>
>
> As best as I can see python makes no distinction between such a foo and
> the more usual function/methods that have no returns.
> You can I can talk about these and distinguish them
> Python has no clue about it.
>

Python *ALWAYS* returns None for any path through a function that 
doesn't specify a return value.  Taking your example.

 >>> def foo(x):
...     if x>0: return x-1
...
 >>> import dis
 >>> dis.dis(foo)
   2           0 LOAD_FAST                0 (x)
               3 LOAD_CONST               1 (0)
               6 COMPARE_OP               4 (>)
               9 POP_JUMP_IF_FALSE       20
              12 LOAD_FAST                0 (x)
              15 LOAD_CONST               2 (1)
              18 BINARY_SUBTRACT
              19 RETURN_VALUE
         >>   20 LOAD_CONST               0 (None)
              23 RETURN_VALUE

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence

Thread

generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-12 06:35 -0700
  Re: generator/coroutine terminology Chris Angelico <rosuav@gmail.com> - 2015-03-13 00:55 +1100
  Re: generator/coroutine terminology breamoreboy@gmail.com - 2015-03-12 06:57 -0700
  Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-13 03:27 +1100
    Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-12 09:52 -0700
      Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-12 19:55 +0200
        Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-12 19:23 -0700
          Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-13 14:30 +1100
            Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-12 22:28 -0700
              Re: generator/coroutine terminology Chris Angelico <rosuav@gmail.com> - 2015-03-13 19:23 +1100
                Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-13 02:12 -0700
                Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-13 11:36 +0200
                Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-14 17:04 +1100
                Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-14 09:54 +0200
                Re: generator/coroutine terminology Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-14 08:04 +0000
                Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-14 10:30 +0200
                Re: generator/coroutine terminology Ian Kelly <ian.g.kelly@gmail.com> - 2015-03-14 14:14 -0600
                Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-14 21:15 -0700
                Re: generator/coroutine terminology Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-14 20:31 +0000
                Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-14 08:29 -0700
                Re: generator/coroutine terminology Chris Angelico <rosuav@gmail.com> - 2015-03-15 02:56 +1100
                Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-14 08:59 -0700
                Re: generator/coroutine terminology Chris Angelico <rosuav@gmail.com> - 2015-03-15 03:14 +1100
                Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-14 09:33 -0700
                Re: generator/coroutine terminology Chris Angelico <rosuav@gmail.com> - 2015-03-15 03:51 +1100
                Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-14 10:17 -0700
                Re: generator/coroutine terminology Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-14 16:56 +0000
                Re: generator/coroutine terminology Dave Angel <davea@davea.name> - 2015-03-14 13:07 -0400
                Re: generator/coroutine terminology albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-03-31 12:57 +0000
                Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-15 19:37 +1100
                Re: generator/coroutine terminology CHIN Dihedral <dihedral88888@gmail.com> - 2015-04-18 11:07 -0700
                Re: generator/coroutine terminology Chris Angelico <rosuav@gmail.com> - 2015-03-13 22:32 +1100
      Re: generator/coroutine terminology Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2015-03-14 22:02 +0000
        Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-15 00:15 +0200
          Re: generator/coroutine terminology Chris Angelico <rosuav@gmail.com> - 2015-03-15 09:24 +1100
            Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-15 02:15 +0200
              Re: generator/coroutine terminology Chris Angelico <rosuav@gmail.com> - 2015-03-15 11:22 +1100
                Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-15 02:48 +0200
                Re: generator/coroutine terminology Chris Angelico <rosuav@gmail.com> - 2015-03-15 13:02 +1100
              Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-16 12:03 +1100
                Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-16 09:12 +0200
                Re: generator/coroutine terminology Chris Angelico <rosuav@gmail.com> - 2015-03-16 18:21 +1100
                Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-16 09:40 +0200
                Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-16 22:59 +1100
                Re: generator/coroutine terminology Ian Kelly <ian.g.kelly@gmail.com> - 2015-03-16 01:37 -0600
                Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-16 09:52 +0200
                Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-16 23:02 +1100
                Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-16 14:42 +0200
                Re: generator/coroutine terminology Jonas Wielicki <jonas@wielicki.name> - 2015-03-16 13:39 +0100
                Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-16 19:36 +1100
                Re: generator/coroutine terminology Chris Angelico <rosuav@gmail.com> - 2015-03-16 19:58 +1100
                Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-16 22:51 +1100
                Re: generator/coroutine terminology Chris Angelico <rosuav@gmail.com> - 2015-03-17 00:16 +1100
                Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-16 14:32 +0200
                Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-16 05:51 -0700
                Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-16 15:13 +0200
                Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-17 01:32 +1100
                Re: generator/coroutine terminology Ian Kelly <ian.g.kelly@gmail.com> - 2015-03-16 08:45 -0600
                Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-17 00:39 +1100
                Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-16 07:19 -0700
                Re: generator/coroutine terminology Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-16 14:26 +0000
                Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-16 07:37 -0700
                Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-16 07:55 -0700
                Re: generator/coroutine terminology Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-16 18:19 +0000
                Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-16 19:52 -0700
                Re: generator/coroutine terminology Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-17 03:07 +0000
                Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-16 20:18 -0700
                Re: generator/coroutine terminology Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-17 03:25 +0000
                Re: generator/coroutine terminology Rustom Mody <rustompmody@gmail.com> - 2015-03-16 20:33 -0700
                Re: generator/coroutine terminology Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-17 03:55 +0000
                Re: generator/coroutine terminology Mario Figueiredo <marfig@gmail.com> - 2015-03-17 04:22 +0100
                Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-17 01:35 +1100
                Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-17 01:36 +1100
                Re: generator/coroutine terminology Ian Kelly <ian.g.kelly@gmail.com> - 2015-03-16 08:52 -0600
                Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-16 17:09 +0200
                Re: generator/coroutine terminology Ian Kelly <ian.g.kelly@gmail.com> - 2015-03-16 09:26 -0600
                Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-16 18:05 +0200
                Re: generator/coroutine terminology albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-03-31 13:18 +0000
                Re: generator/coroutine terminology Dave Angel <davea@davea.name> - 2015-03-31 09:38 -0400
                Re: generator/coroutine terminology albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-03-31 15:03 +0000
                Re: generator/coroutine terminology Chris Angelico <rosuav@gmail.com> - 2015-04-01 02:36 +1100
                Re: generator/coroutine terminology Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-03 17:02 +1100
                Re: generator/coroutine terminology albert@spenarnc.xs4all.nl (Albert van der Horst) - 2015-04-18 17:52 +0000
                Re: generator/coroutine terminology Paul Rubin <no.email@nospam.invalid> - 2015-04-02 23:46 -0700
  Re: generator/coroutine terminology Terry Reedy <tjreedy@udel.edu> - 2015-03-12 16:11 -0400
    Re: generator/coroutine terminology Marko Rauhamaa <marko@pacujo.net> - 2015-03-12 22:22 +0200

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