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Re: Documentation of dict views change request

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In article <mailman.5728.1390166846.18130.python-list@python.org>,
 Charles Hixson <charleshixsn@earthlink.net> wrote:

> Could it please be clearly documented that keys(), values(), and items() 
> are not writeable.

We'll, technically, they are.

>>> d = {'foo': 1, 'bar':2}
>>> k = d.keys()
>>> k
['foo', 'bar']
>>> k[0] = "some other key"
>>> k
['some other key', 'bar']

Of course, this only changes the list that keys() returns, it doesn't 
affect the dictionary itself (which, I assume, is what you were really 
talking about).

Think this one through.  How *could* altering what keys() returns 
possibly affect the dict?  If it did, that means you could do something 
like:

some_dict.keys().append("some other key")

what would that mean?  You've added a key, but what's the corresponding 
value?  I will admit, the picture becomes a bit fuzzier if you consider:

some_dict.items().append(("some other key", 42))

which you could at least imagine would affect the underlying dict.

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Documentation of dict views change request Charles Hixson <charleshixsn@earthlink.net> - 2014-01-19 13:26 -0800
  Re: Documentation of dict views change request Roy Smith <roy@panix.com> - 2014-01-20 03:10 +0530
    Re: Documentation of dict views change request Chris Angelico <rosuav@gmail.com> - 2014-01-20 08:56 +1100

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