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Re: __bases__ misleading error message

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From Terry Reedy <tjreedy@udel.edu>
Subject Re: __bases__ misleading error message
Date Sat, 24 Jan 2015 16:58:10 -0500
References <1a194e0a0b738d205de54180fa7@nntp.aioe.org> <54c39366$0$13006$c3e8da3$5496439d@news.astraweb.com> <MPG.2f2e298c14dbed69989692@nntp.aioe.org>
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On 1/24/2015 4:14 PM, Mario Figueiredo wrote:
> In article <54c39366$0$13006$c3e8da3$5496439d@news.astraweb.com>,
> steve+comp.lang.python@pearwood.info says...
>>>          AttributeError: 'Sub' instance has no attribute '__bases__',
>>>          AttributeError: 'foo' object has no attribute '__bases__'
>>
>> The first would be nice. The second is impossible: objects may have no name,
>> one name, or many names, and they do not know what names they are bound to.
>> So the Sub instance bound to the name 'foo' doesn't know that its name
>> is 'foo', so it cannot display it in the error message.
>
> Thanks for the information! :)
>
> But that begs the OT question: How does Python maps names to memory
> addresses in the interpreter?

Python the language maps names to objects that have identity, type, and 
value.  The CPython implementation does the mapping with a hash table 
and C pointers (to computer memory addresses), but addresses are not 
part of the language definition.  Neuroscientists still puzzle over how 
we do such mapping.

>      "__main__"
>      from module import a_name

A module is a namespace associating names with objects.  This statememt 
says to import the a_name to object association from module and add it 
to __main__

>      y = a_name + 1

This statement uses the imported association in __main__ to access the 
object and add 1, and bind 'y' to the resulting object.

-- 
Terry Jan Reedy

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Thread

__bases__ misleading error message Mario Figueiredo <marfig@gmail.com> - 2015-01-24 10:16 +0000
  Re: __bases__ misleading error message Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-24 23:43 +1100
    Re: __bases__ misleading error message Mario Figueiredo <marfig@gmail.com> - 2015-01-24 22:14 +0100
      Re: __bases__ misleading error message Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-24 14:45 -0700
        Re: __bases__ misleading error message Mario Figueiredo <marfig@gmail.com> - 2015-01-24 23:09 +0100
          Re: __bases__ misleading error message Chris Angelico <rosuav@gmail.com> - 2015-01-25 09:25 +1100
            Re: __bases__ misleading error message Mario Figueiredo <marfig@gmail.com> - 2015-01-24 23:33 +0100
              Re: __bases__ misleading error message Chris Angelico <rosuav@gmail.com> - 2015-01-25 09:37 +1100
                Re: __bases__ misleading error message Mario Figueiredo <marfig@gmail.com> - 2015-01-24 23:59 +0100
      Re: __bases__ misleading error message Terry Reedy <tjreedy@udel.edu> - 2015-01-24 16:58 -0500
        Re: __bases__ misleading error message Mario Figueiredo <marfig@gmail.com> - 2015-01-24 23:02 +0100
          Re: __bases__ misleading error message Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-24 15:16 -0700
            Re: __bases__ misleading error message Mario Figueiredo <marfig@gmail.com> - 2015-01-24 23:36 +0100
      Re: __bases__ misleading error message Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-25 14:18 +1100
        Re: __bases__ misleading error message Mario Figueiredo <marfig@gmail.com> - 2015-01-25 12:07 +0100
          Re: __bases__ misleading error message Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-25 23:00 +1100
            Re: __bases__ misleading error message Mario Figueiredo <marfig@gmail.com> - 2015-01-25 13:49 +0100
              Re: __bases__ misleading error message Marko Rauhamaa <marko@pacujo.net> - 2015-01-25 14:53 +0200
            Re: __bases__ misleading error message Terry Reedy <tjreedy@udel.edu> - 2015-01-25 16:35 -0500
            Re: __bases__ misleading error message Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-25 19:21 -0700
    Re: __bases__ misleading error message Marco Buttu <marco.buttu@gmail.com> - 2015-01-24 23:09 +0100
    Re: __bases__ misleading error message Marco Buttu <marco.buttu@gmail.com> - 2015-01-24 15:12 +0100
  Re: __bases__ misleading error message Terry Reedy <tjreedy@udel.edu> - 2015-01-24 14:24 -0500
    Re: __bases__ misleading error message Mario Figueiredo <marfig@gmail.com> - 2015-01-24 22:03 +0100
    Re: __bases__ misleading error message Marco Buttu <marco.buttu@gmail.com> - 2015-01-24 22:51 +0100
      Re: __bases__ misleading error message Terry Reedy <tjreedy@udel.edu> - 2015-01-24 19:55 -0500
        Re: __bases__ misleading error message Marco Buttu <marco.buttu@gmail.com> - 2015-01-25 11:30 +0100
    Re: __bases__ misleading error message Marco Buttu <marco.buttu@gmail.com> - 2015-01-24 22:51 +0100

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