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Re: Objects in Python

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Date Wed, 22 Aug 2012 21:31:51 +0100
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On 22/08/2012 20:45, lipska the kat wrote:
> On 22/08/12 20:03, Evan Driscoll wrote:
>> On 08/22/2012 12:46 PM, lipska the kat wrote:
>>> If you can show me a 'type' that cannot be assigned to
>>>
>>> a
>>>
>>> in the same scope then I would be most interested to know, I haven't
>>> found one yet.
>>
> [snip]
>
>>
>> Second, this concept isn't *so* unfamiliar to you. If I give you the
>> following Java code:
>>
>>    void foo(Object o) { ... }
>>
>> and ask what type 'o' is, there are kind of two answers. The first is
>> that 'o' is an 'Object'. But you can't make an Object -- that's an
>> abstract class. (IIRC. If it's not then just bear with me; you get the
>> idea. :-)) So from a strictly static type-theory point of view, 'foo' is
>> unusable because it takes a type which you can never create. But of
>> course that's not the case, because in actual Java 'o' has some dynamic
>> type which is a subclass of 'Object'.
>
> Well I think this is where I'm struggling a bit.
>
> looking at this method declaration I can see that the method takes an
> argument of type Object (and just FYI class Object is not abstract and
> you can do Object o = new Object()) and does not return a value.
> I know that for the lifetime of this JVM, whatever o turns out to be it
> will always be an Object. I can't assign a primitive to o as ints chars
> floats etc are certainly not Objects. There are certain invariants that
> give me a warm and comfortable feeling inside.
>
> compare this to a function declaration in Python
>
> def foo(self):
>
[snip]
That's not actually a declaration but a definition. :-)

The function's body is bound to the name at runtime, so:

     def double_it(x):
         return x * 2

is not far from:

     double_it = lambda x: x * 2

The only declarations are "global" and "nonlocal" (and the latter
exists only in recent versions of Python).

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Thread

Objects in Python shaun <shaun.wiseman91@gmail.com> - 2012-08-22 07:13 -0700
  Re: Objects in Python Joel Goldstick <joel.goldstick@gmail.com> - 2012-08-22 10:31 -0400
  Re: Objects in Python Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2012-08-22 17:31 +0300
  Re: Objects in Python Peter Otten <__peter__@web.de> - 2012-08-22 16:36 +0200
  Re: Objects in Python lipska the kat <lipskathekat@yahoo.co.uk> - 2012-08-22 15:59 +0100
    Re: Objects in Python MRAB <python@mrabarnett.plus.com> - 2012-08-22 16:58 +0100
      Re: Objects in Python lipska the kat <lipskathekat@yahoo.co.uk> - 2012-08-22 17:10 +0100
        Re: Objects in Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-22 17:30 +0100
          Re: Objects in Python lipska the kat <lipskathekat@yahoo.co.uk> - 2012-08-22 18:06 +0100
            Re: Objects in Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-22 19:07 +0100
              Re: Objects in Python lipska the kat <lipskathekat@yahoo.co.uk> - 2012-08-22 20:13 +0100
    Re: Objects in Python Terry Reedy <tjreedy@udel.edu> - 2012-08-22 13:01 -0400
      Re: Objects in Python lipska the kat <lipskathekat@yahoo.co.uk> - 2012-08-22 18:46 +0100
        Re: Objects in Python Ian Kelly <ian.g.kelly@gmail.com> - 2012-08-22 12:15 -0600
          Re: Objects in Python lipska the kat <lipskathekat@yahoo.co.uk> - 2012-08-22 20:03 +0100
            Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-23 12:02 +1000
              Re: Objects in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-23 04:11 +0000
                Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-23 15:26 +1000
                Re: Objects in Python Jan Kuiken <jan.kuiken@quicknet.nl> - 2012-08-23 20:02 +0200
                Re: Objects in Python Ian Kelly <ian.g.kelly@gmail.com> - 2012-08-23 12:17 -0600
                Re: Objects in Python Jan Kuiken <jan.kuiken@quicknet.nl> - 2012-08-23 22:43 +0200
                Re: Objects in Python 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-25 23:14 -0700
        Re: Objects in Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-22 19:23 +0100
        Re: Re: Objects in Python Evan Driscoll <driscoll@cs.wisc.edu> - 2012-08-22 14:03 -0500
          Re: Objects in Python lipska the kat <lipskathekat@yahoo.co.uk> - 2012-08-22 20:45 +0100
            Re: Objects in Python MRAB <python@mrabarnett.plus.com> - 2012-08-22 21:31 +0100
            Re: Objects in Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-22 21:46 +0100
              Methods versus functions [was Re: Objects in Python] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-23 04:07 +0000
            Re: Re: Objects in Python Evan Driscoll <driscoll@cs.wisc.edu> - 2012-08-22 16:31 -0500
              Re: Objects in Python lipska the kat <lipskathekat@yahoo.co.uk> - 2012-08-23 10:19 +0100
                Re: Re: Objects in Python Evan Driscoll <driscoll@cs.wisc.edu> - 2012-08-23 11:44 -0500
                Re: Objects in Python lipska the kat <lipskathekat@yahoo.co.uk> - 2012-08-23 18:56 +0100
        Re: Objects in Python Ben Finney <ben+python@benfinney.id.au> - 2012-08-23 09:58 +1000
          Re: Objects in Python Ian Kelly <ian.g.kelly@gmail.com> - 2012-08-22 18:10 -0600
          Re: Re: Objects in Python Evan Driscoll <driscoll@cs.wisc.edu> - 2012-08-22 23:49 -0500
            Re: Objects in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-23 06:55 +0000
              Re: Objects in Python Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2012-08-23 11:59 +0300
                Re: Objects in Python MRAB <python@mrabarnett.plus.com> - 2012-08-23 12:28 +0100
                Re: Objects in Python Jerry Hill <malaclypse2@gmail.com> - 2012-08-23 10:43 -0400
                Re: Objects in Python Evan Driscoll <driscoll@cs.wisc.edu> - 2012-08-23 12:17 -0500
                Re: Objects in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-23 17:56 +0000
                Variables vs names [was: Objects in Python] Evan Driscoll <driscoll@cs.wisc.edu> - 2012-08-23 14:22 -0500
                Re: Variables vs names Ben Finney <ben+python@benfinney.id.au> - 2012-08-24 10:02 +1000
                Re: Variables vs names [was: Objects in Python] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-25 02:05 +0000
                Re: Variables vs names Ben Finney <ben+python@benfinney.id.au> - 2012-08-25 15:24 +1000
                Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-24 08:00 +1000
                Re: Objects in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-25 03:04 +0000
                Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-25 16:34 +1000
                Re: Objects in Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-25 09:55 +0100
                Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-25 20:23 +1000
                Re: Objects in Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-25 12:01 +0100
                Re: Objects in Python Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-08-25 15:56 -0400
                Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-26 09:27 +1000
                Re: Objects in Python Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-08-25 20:43 -0400
                Re: Re: Objects in Python Evan Driscoll <driscoll@cs.wisc.edu> - 2012-08-26 00:25 -0500
                Re: Variables vs names [was: Objects in Python] Chris Angelico <rosuav@gmail.com> - 2012-08-24 09:34 +1000
                Re: Objects in Python Ben Finney <ben+python@benfinney.id.au> - 2012-08-24 09:49 +1000
                Re: Variables vs names [was: Objects in Python] Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-08-23 19:52 -0400
                Re: Objects in Python Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-08-23 19:54 -0400
                Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-24 10:01 +1000
                Re: Objects in Python Terry Reedy <tjreedy@udel.edu> - 2012-08-23 13:17 -0400
            Re: Objects in Python Ben Finney <ben+python@benfinney.id.au> - 2012-08-24 00:16 +1000
            Re: Objects in Python Roy Smith <roy@panix.com> - 2012-08-23 20:36 -0400
              Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-24 11:34 +1000
                Re: Objects in Python alex23 <wuwei23@gmail.com> - 2012-08-23 20:17 -0700
                Re: Re: Objects in Python Evan Driscoll <driscoll@cs.wisc.edu> - 2012-08-24 04:14 -0500
                Re: Objects in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-24 10:00 +0000
                Re: Objects in Python Grant Edwards <invalid@invalid.invalid> - 2012-08-24 13:27 +0000
                Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-25 05:18 +1000
                Re: Re: Objects in Python Evan Driscoll <driscoll@cs.wisc.edu> - 2012-08-26 00:45 -0500
                Re: Objects in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-26 13:43 +0000
                Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-26 23:58 +1000
                Re: Objects in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-26 14:18 +0000
                Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-27 00:54 +1000
                Re: Objects in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-26 22:47 +0000
                Re: Objects in Python Roy Smith <roy@panix.com> - 2012-08-26 10:02 -0400
                Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-27 00:14 +1000
                Re: Objects in Python Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-08-26 16:12 -0400
                Re: Objects in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-26 23:29 +0000
                Re: Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-26 16:22 +1000
                Re: Objects in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-26 12:02 +0000
                Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-26 23:34 +1000
                Re: Objects in Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-26 15:02 +0100
                Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-27 00:05 +1000
                Re: Objects in Python Roy Smith <roy@panix.com> - 2012-08-26 09:41 -0400
              Identity function id() [was Re: Objects in Python] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-24 10:06 +0000
          Re: Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-23 15:33 +1000
          Re: Objects in Python Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-08-23 14:30 -0400
            Re: Objects in Python Alexander Blinne <news@blinne.net> - 2012-08-24 15:23 +0200
          Re: Objects in Python Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2012-08-24 09:38 +0200
          Re: Objects in Python Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2012-08-24 10:03 +0200
        Re: Objects in Python Walter Hurry <walterhurry@lavabit.com> - 2012-08-23 01:19 +0000
          Re: Objects in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-23 04:14 +0000
            Re: Objects in Python lipska the kat <lipskathekat@yahoo.co.uk> - 2012-08-23 09:10 +0100
              Re: Objects in Python Ben Finney <ben+python@benfinney.id.au> - 2012-08-23 23:59 +1000
                Re: Objects in Python lipska the kat <lipskathekat@yahoo.co.uk> - 2012-08-23 15:20 +0100
                Re: Objects in Python Ben Finney <ben+python@benfinney.id.au> - 2012-08-24 00:24 +1000
          Re: Objects in Python lipska the kat <lipskathekat@yahoo.co.uk> - 2012-08-23 09:03 +0100
        Re: Objects in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-08-23 04:34 +0000
          Re: Objects in Python rusi <rustompmody@gmail.com> - 2012-08-23 10:04 -0700
  Re: Objects in Python John Gordon <gordon@panix.com> - 2012-08-22 15:03 +0000
  Re: Objects in Python shaun <shaun.wiseman91@gmail.com> - 2012-08-22 08:25 -0700
    Re: Objects in Python Chris Angelico <rosuav@gmail.com> - 2012-08-23 01:47 +1000
    Re: Objects in Python Dave Angel <d@davea.name> - 2012-08-22 11:51 -0400
    Re: Objects in Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-08-22 17:13 +0100
    Re: Objects in Python Ian Kelly <ian.g.kelly@gmail.com> - 2012-08-22 11:29 -0600

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