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To: python-list@python.org
From: Terry Reedy <tjreedy@udel.edu>
Subject: Re: Documentation of dict views change request
Date: Sun, 19 Jan 2014 18:22:07 -0500
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On 1/19/2014 4:41 PM, Mark Lawrence wrote:
> On 19/01/2014 21:26, Charles Hixson wrote:
>> Could it please be clearly documented that keys(), values(), and items=
()
>> are not writeable.  I agree that this is how they should be, but it
>> would be still better if they were clearly documented as such.  The
>> labeling of them as dynamic, while true, was a bit confusing here.
>> (I.e., it was talking about changing their value through other means o=
f
>> access rather than directly through the returned values.)
>>
>> P.S.:  Is it reasonable to return the items() of a dict in order to pa=
ss
>> a read only copy of the values?
>>
>
> Just raise an issue here http://bugs.python.org/

The relevant section is

4.10.1. Dictionary view objects=C2=B6

The objects returned by dict.keys(), dict.values() and dict.items() are=20
view objects.

The 'view object' are implicitly 'read-only' because no syntax is given=20
to write to them, but ahead and propose adding 'read-only' to make the=20
above explicitly say "read-only view objects".

--=20
Terry Jan Reedy