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Groups > comp.lang.python > #105694
| From | Ethan Furman <ethan@stoneleaf.us> |
|---|---|
| Newsgroups | comp.lang.python |
| Subject | Re: Effects of caching frequently used objects, was Re: Explaining names vs variables in Python |
| Date | 2016-03-25 09:45 -0700 |
| Message-ID | <mailman.4.1458924289.28225.python-list@python.org> (permalink) |
| References | <nb6aqh$dp5$1@ger.gmane.org> <DUB123-W22AD13A14B7564949220F683830@phx.gbl> |
On 03/25/2016 06:03 AM, Albert-Jan Roskam wrote: > Somebody wrote: >> Somebody else wrote: >>> I know Python does not have variables, but names. >>> Multiple names cant then be bound to the same objects. >>> >>> So this behavior >>> >>>--> b = 234 >>>--> v = 234 >>>--> b is v >>> True >>> >>> according to the above that is ok >>> >>> >>> >>> But where is the consistency ? if I try : >>> >>>--> v = 890 >>>--> w = 890 >>>--> v is w >>> False >>> >>> It is a little difficult to explain this behavior to a newcommer in Python >>> >>> Can someone give me the right argument to expose ? >> >> You should not bother with object identity for objects other than None. No. The correct answer is: if identity is important either ensure the object you are getting back is a singleton (such as None, True, an Enum member, etc.) or you assign one name from another name: --> b = 234 --> v = b --> b is v True --> v = 890 --> w = v --> v is w True If identity is not important, don't use `is`. > A little late to the party, but: how about Ellipsis? Shouldn't "is" also be used for that one? (It's rare, I know :)) Ellipsis is a singleton, so `is` is fine. -- ~Ethan~
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Explaining names vs variables in Python Salvatore DI DIO <salvatore.didio@gmail.com> - 2016-03-02 00:32 -0800
Re: Explaining names vs variables in Python Jesper K Brogaard <jesper@brogAAaard.eu> - 2016-03-02 10:03 +0100
Re: Explaining names vs variables in Python Steven D'Aprano <steve@pearwood.info> - 2016-03-02 21:32 +1100
Re: Explaining names vs variables in Python Marko Rauhamaa <marko@pacujo.net> - 2016-03-02 14:34 +0200
Re: Explaining names vs variables in Python Chris Angelico <rosuav@gmail.com> - 2016-03-02 23:50 +1100
Re: Explaining names vs variables in Python Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-02 15:11 +0200
Re: Explaining names vs variables in Python Marko Rauhamaa <marko@pacujo.net> - 2016-03-02 15:39 +0200
Re: Explaining names vs variables in Python Chris Angelico <rosuav@gmail.com> - 2016-03-03 00:48 +1100
Re: Explaining names vs variables in Python Marko Rauhamaa <marko@pacujo.net> - 2016-03-02 16:11 +0200
Re: Explaining names vs variables in Python Rustom Mody <rustompmody@gmail.com> - 2016-03-02 07:08 -0800
Re: Explaining names vs variables in Python Steven D'Aprano <steve@pearwood.info> - 2016-03-03 04:23 +1100
Re: Explaining names vs variables in Python Rustom Mody <rustompmody@gmail.com> - 2016-03-02 09:28 -0800
Re: Explaining names vs variables in Python Marko Rauhamaa <marko@pacujo.net> - 2016-03-02 20:12 +0200
Re: Explaining names vs variables in Python Steven D'Aprano <steve@pearwood.info> - 2016-03-03 12:52 +1100
Re: Explaining names vs variables in Python Rustom Mody <rustompmody@gmail.com> - 2016-03-03 09:03 -0800
Re: Explaining names vs variables in Python Ian Kelly <ian.g.kelly@gmail.com> - 2016-03-03 12:53 -0700
Re: Explaining names vs variables in Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-02 21:49 +0000
Re: Explaining names vs variables in Python Steven D'Aprano <steve@pearwood.info> - 2016-03-03 13:05 +1100
Re: Explaining names vs variables in Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-03 16:09 +0000
Re: Explaining names vs variables in Python Chris Angelico <rosuav@gmail.com> - 2016-03-03 08:52 +1100
Re: Explaining names vs variables in Python Rustom Mody <rustompmody@gmail.com> - 2016-03-02 17:23 -0800
Re: Explaining names vs variables in Python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-02 22:51 +0000
Re: Explaining names vs variables in Python Steven D'Aprano <steve@pearwood.info> - 2016-03-03 04:10 +1100
Re: Explaining names vs variables in Python Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-02 10:08 +0100
Effects of caching frequently used objects, was Re: Explaining names vs variables in Python Peter Otten <__peter__@web.de> - 2016-03-02 10:12 +0100
Re: Explaining names vs variables in Python Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-02 11:35 +0200
Re: Explaining names vs variables in Python Ian Kelly <ian.g.kelly@gmail.com> - 2016-03-02 08:13 -0700
Re: Explaining names vs variables in Python Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-02 17:37 +0200
Re: Explaining names vs variables in Python Steven D'Aprano <steve@pearwood.info> - 2016-03-02 21:16 +1100
Re: Explaining names vs variables in Python "ast" <nomail@invalid.com> - 2016-03-02 11:52 +0100
Re: Explaining names vs variables in Python Salvatore DI DIO <salvatore.didio@gmail.com> - 2016-03-02 02:58 -0800
Re: Effects of caching frequently used objects, was Re: Explaining names vs variables in Python Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-03-02 09:16 -0500
Re: Explaining names vs variables in Python Ben Finney <ben+python@benfinney.id.au> - 2016-03-03 04:53 +1100
RE: Effects of caching frequently used objects, was Re: Explaining names vs variables in Python Albert-Jan Roskam <sjeik_appie@hotmail.com> - 2016-03-25 13:03 +0000
Re: Effects of caching frequently used objects, was Re: Explaining names vs variables in Python Chris Angelico <rosuav@gmail.com> - 2016-03-26 00:22 +1100
Re: Effects of caching frequently used objects, was Re: Explaining names vs variables in Python Ethan Furman <ethan@stoneleaf.us> - 2016-03-25 09:45 -0700
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