Explanation of list reference

Mark Lawrence breamoreboy at yahoo.co.uk
Sun Feb 16 19:36:44 CET 2014


On 16/02/2014 18:01, Marko Rauhamaa wrote:
> Rustom Mody <rustompmody at gmail.com>:
>
>> But for that Ive to use is
>> And as a teacher Ive to explain is
>> Might as well use C and get on with pointers
>>
>> To me 'is' is a can of worms
>
> I'm not against "is," but it must be carefully defined and taught.
>
> As far as "x is None" is concerned, a key piece of information is
> presented on <URL: http://docs.python.org/3.2/library/constants.html>:
>
>    None
>      The sole value of the type NoneType.
>
> Unfortunately the page is a bit confusing. It says:
>
>    A small number of constants live in the built-in namespace.
>
> So an essential characteristic of the None object (uniqueness) is
> mentioned in the middle of the discussion on the built-in namespace. The
> index doesn't contain an entry on NoneType.
>
> Thus, there might still be a nagging concern that a second NoneType
> object x such that
>
>     x == None and x is not None
>
> could crop up (from native code, perhaps).
>
>
> Marko
>

Patches are always welcome :)

-- 
My fellow Pythonistas, ask not what our language can do for you, ask 
what you can do for our language.

Mark Lawrence

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