Python 3: dict & dict.keys()
alex23
wuwei23 at gmail.com
Thu Jul 25 02:01:25 EDT 2013
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.
More information about the Python-list
mailing list