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Groups > comp.lang.python > #43754
| Date | 2013-04-17 07:07 -0400 |
|---|---|
| From | Dave Angel <davea@davea.name> |
| Subject | Re: Atoms, Identifiers, and Primaries |
| References | <66e78281-542b-41b3-a56d-04bf736d1e0a@googlegroups.com> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.720.1366196886.3114.python-list@python.org> (permalink) |
On 04/16/2013 10:57 PM, Bruce McGoveran wrote:
> These are terms that appear in section 5 (Expressions) of the Python online documentation. I'm having some trouble understanding what, precisely, these terms mean. I'd appreciate the forum's thoughts on these questions:
>
>
> 3. Section 5.3.1 offers this definition of an attributeref:
> attributeref ::= primary "." identifier
>
> Now, I was at first a little concerned to see the non-terminal primary on the right hand side of the definition, since primary is defined to include attributeref in section 5.3 (so this struck me as circular). Am I correct in thinking attributeref is defined this way to allow for situations in which the primary, whether an atom, attributeref (example: an object on which a method is called that returns another object), subscription, slicing, or call, returns an object with property identifier?
>
It is circular. Nothing wrong with that. It means that not only can
you use
a.b
but also
a.b.c
and
a.b.c.d.e.f.g
without any explicit limit. if a non-circular definition were to be
attempted, you might need a few dozen rules, just to cover what someone
*might* happen to use in an expression. Of course normally, one doesn't
go much beyond a.b.c in a single expression.
--
DaveA
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Atoms, Identifiers, and Primaries Bruce McGoveran <bruce.mcgoveran@gmail.com> - 2013-04-16 19:57 -0700
Re: Atoms, Identifiers, and Primaries rusi <rustompmody@gmail.com> - 2013-04-16 20:55 -0700
Re: Atoms, Identifiers, and Primaries Mark Janssen <dreamingforward@gmail.com> - 2013-04-17 16:40 -0700
Re: Atoms, Identifiers, and Primaries alex23 <wuwei23@gmail.com> - 2013-04-17 17:29 -0700
Re: Atoms, Identifiers, and Primaries Mark Janssen <dreamingforward@gmail.com> - 2013-04-17 17:41 -0700
Re: Atoms, Identifiers, and Primaries Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-04-18 02:04 +0100
Re: Atoms, Identifiers, and Primaries rusi <rustompmody@gmail.com> - 2013-04-18 00:40 -0700
Re: Atoms, Identifiers, and Primaries Ian Kelly <ian.g.kelly@gmail.com> - 2013-04-17 18:33 -0600
Re: Atoms, Identifiers, and Primaries Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-04-18 02:14 +0000
Re: Atoms, Identifiers, and Primaries Ian Kelly <ian.g.kelly@gmail.com> - 2013-04-17 21:12 -0600
Re: Atoms, Identifiers, and Primaries Mark Janssen <dreamingforward@gmail.com> - 2013-04-17 18:04 -0700
Re: Atoms, Identifiers, and Primaries Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-04-18 02:08 +0100
Re: Atoms, Identifiers, and Primaries Chris Angelico <rosuav@gmail.com> - 2013-04-18 11:56 +1000
Re: Atoms, Identifiers, and Primaries Ian Kelly <ian.g.kelly@gmail.com> - 2013-04-17 21:10 -0600
Re: Atoms, Identifiers, and Primaries Ian Kelly <ian.g.kelly@gmail.com> - 2013-04-17 01:21 -0600
Re: Atoms, Identifiers, and Primaries 88888 Dihedral <dihedral88888@googlemail.com> - 2013-04-17 21:29 -0700
Re: Atoms, Identifiers, and Primaries 88888 Dihedral <dihedral88888@googlemail.com> - 2013-04-17 21:29 -0700
Re: Atoms, Identifiers, and Primaries Dave Angel <davea@davea.name> - 2013-04-17 07:07 -0400
Re: Atoms, Identifiers, and Primaries Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-04-17 11:43 +0000
Re: Atoms, Identifiers, and Primaries Bruce McGoveran <bruce.mcgoveran@gmail.com> - 2013-04-17 10:15 -0700
Re: Atoms, Identifiers, and Primaries Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-04-18 04:43 +1000
Re: Atoms, Identifiers, and Primaries rusi <rustompmody@gmail.com> - 2013-04-18 10:04 -0700
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