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Re: Python 3: dict & dict.keys()

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On 25/07/2013 4:31 AM, Ethan Furman wrote:
>    2) Hopefully learn something about when a view is useful.

I haven't seeen this mentioned - forgive me if it's a repeat - but views 
are constant references to whichever set they represent.

Python 2.7:

 >>> dd = dict(a=1,b=2,c=3)
 >>> keys = dd.keys()
 >>> 'a' in keys
True
 >>> dd['d'] = 4
 >>> 'd' in keys
False

Python 3.3:
 >>> dd = dict(a=1,b=2,c=3)
 >>> keys = dd.keys()
 >>> 'a' in keys
True
 >>> dd['d'] = 4
 >>> 'd' in keys
True

If part of my code is only interested in what keys or values are 
present, it doesn't need to be given a reference to the full dictionary, 
just to whichever view it cares about.

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Re: Python 3: dict & dict.keys() Ethan Furman <ethan@stoneleaf.us> - 2013-07-24 11:31 -0700
  Re: Python 3: dict & dict.keys() alex23 <wuwei23@gmail.com> - 2013-07-25 16:01 +1000
    Re: Python 3: dict & dict.keys() Ethan Furman <ethan@stoneleaf.us> - 2013-07-25 06:47 -0700
  Re: Python 3: dict & dict.keys() Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-07-25 07:04 +0000
    Re: Python 3: dict & dict.keys() Chris Angelico <rosuav@gmail.com> - 2013-07-25 18:02 +1000
    Re: Python 3: dict & dict.keys() Peter Otten <__peter__@web.de> - 2013-07-25 10:13 +0200
    Re: Python 3: dict & dict.keys() Ian Kelly <ian.g.kelly@gmail.com> - 2013-07-25 09:53 -0600
    Re: Python 3: dict & dict.keys() Peter Otten <__peter__@web.de> - 2013-07-25 18:25 +0200

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